Java Basics Lecture Notes

how&#39;s it going everybody it&#39;s bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys everything you need to know to get started with java so sit back relax and enjoy the show if you wouldn&#39;t mind please like comment and subscribe one like equals one prayer for the youtube algorithm here&#39;s an outline of the topics covered in this video if you would like to skip ahead to a certain section feel free to click on any of the timestamps posted in the description also at the end of this video we&#39;re going to be discussing some tips and tricks so be sure to watch until the very end i&#39;ll give you three reasons why you need to learn java besides being one of the top three most popular programming languages worldwide java is an extremely flexible language it&#39;s used extensively by business enterprises android apps games and if you learn java you could land a job as a java developer according to glassdoor entry-level java developers have an average starting salary of 70 000 that&#39;s nothing to sneeze at so why not learn java are you still here okay cool let&#39;s begin with the basics computer languages are on a spectrum between being high level and low level computers only understand binary it&#39;s referred to as machine code it&#39;s a low level format that a machine can understand however humans have difficulty reading binary since it&#39;s all ones and zeros to create machine code we write in a format called source code which is understandable by humans and compile to machine code when we create javasource code the file ends with a dot java file extension think of compiling code as transforming source code to machine code we do this because machines can&#39;t read source code and vice versa humans have trouble reading machine code unless you&#39;re a robot or an android or something however when we compile our source code to machine code it&#39;s machine specific if we write source code and compile on a mac we can only run that code on a mac and the same concept applies for pcs although the java language has a solution for this problem with java we have an intermediary step where we can compile our source code to a format called bytecode bytecode is cross platform and ends with a dot class file extension here&#39;s an example of java source code and here&#39;s an example of that same source code after we compile it to bytecode it&#39;s kind of funky right since bytecode is cross-platform you could write your code on a mac and then send your bytecode file to your friend who can then run it on their pc using a jvm to translate the bytecode to machine code but we are going to need the help of a jvm to translate bytecode to machine code but where can we get a jvm well it&#39;s included with a jdk and what is a jdk well jdk is an acronym for java development kit it contains developers tools to help us code as well as a jre a java runtime environment which contains a library toolkits and our jvm which is another acronym for java virtual machine which translates by code for us to machine code so all you need to worry about is downloading a jdk and everything else will be included and now that we know what a jdk is it&#39;s time to download one so open up the internet and go to any search engine and look this up java jdk download go to the first link java se downloads sc stands for standard edition go to jdk download scroll down and find the appropriate file for your operating system since i&#39;m running windows i&#39;m going to download this exe version agree to whatever and download and when this finishes downloading i&#39;m going to open this open when done on my computer i currently have a jdk already installed but i&#39;m going to go ahead and reinstall it for the sake of this video click next next then wait a little bit and close i would also recommend an ide that&#39;s another acronym and it stands for integrated development environment think of it as software that helps us write other software you could write code with a text editor such as notepad and then compile the text file but doing so is not really beginner friendly so an ide provides an interface for us to write code check for errors compile and run code there&#39;s two ides that i would recommend they are both eclipse or intellij idea it doesn&#39;t matter which one you download because the code that we write is still the same so let&#39;s download an ide now it&#39;s time to install the ide i would recommend either the eclipse ide or intellij idea i&#39;m more comfortable with eclipse so i&#39;m going to stick with the clips so go back to the interwebs and look up either eclipse ide or intellij idea ide so i&#39;m going to look up the clips click the first link click this orange download button go to download packages and select eclipse ide for java developers and select the correct download for your machine i&#39;m going to select the download for windows and click download and then just wait a little bit again like usual for me this is currently a zip file so i need to select this file and extract all with the newly extracted folder navigate to this eclipse application so you can select this to launch eclipse for convenience i&#39;m going to create a desktop shortcut so for me i&#39;m going to go to where is it send to create desktop shortcut and then click to launch you can select a workspace i&#39;m going to use the default and click launch we are now within eclipse and we can begin a new project we are now ready to rock and roll so let&#39;s begin by creating our first java program but in order to do so we need to create a java project if you&#39;re brought to this welcome screen you can close out of this because it&#39;s annoying and in order to create a java project navigate to your package explorer and select create a java project if you&#39;re missing the package explorer you can go to file new dropper project and that will take you to the same place we need a unique name for this java project i will call this my first program and i will want to configure the jre the java runtime environment and we downloaded that with the jdk because the jre is a component of the jdk so i&#39;m currently using 13. i&#39;m going to change this to 15. that was the one that i more recently downloaded just now so go to configure jres and i&#39;m going to click add select standard vm vm is virtual machine click next go to jre home go to directory and i&#39;m going to make sure that i&#39;m selecting the most recent jdk for me that is 15 select folder finish apply apply and close then finish if this window pops up you can select don&#39;t create that&#39;s to create a module if you look to the left hand side within the projects folder we now have a java project called my first program but we will need to add what is called a class to this project a class is a collection of related code so in order to add a class to this project i&#39;m going to select this project folder then go to file new class and we need a unique name for this class i usually call this main but you can name it whatever you want and then we are going to check this public static void main checkbox and then click finish with that out of the way take a look back within your project folder and you should now have a java file that shares the same name as your class name my class name is named main therefore my java file is also called main so this has the dot java file extension and with what we discussed before this is source code it&#39;s in a format that humans can easily read and understand and when we compile this source code to bytecode we&#39;re going to create a new file that has the dot class file extension and with that bytecode file we can run that and translate it using a jvm a java virtual machine here&#39;s our java file and we have our class and mine is called main so all the class is is that it&#39;s a collection of related code we won&#39;t be exploring in depth on the topic of classes until we reach the subject of object-oriented programming which is about 20 videos into this playlist so you have some time so this is our class mine is called main anything within the outer set of curly braces belongs to the class and is contained within and within our class we have what is called a main method our program won&#39;t run without this method because when we run our code we begin by calling the main method so if we were to compile and run this code you can do so by clicking the screenplay button all output is displayed to the console window and nothing appears to happen because we haven&#39;t written anything yet so if we were to remove this main method and tried to do this again we would encounter an error because our main method was not found in the class main it&#39;s asking us to please define the main method now looking back when we created our class we went to file new class and in order to generate the main method we checked this checkbox here that states public static void main so the main method generated for us when we created this class but if we&#39;re missing it we can easily just type it in a textbook that i read in college said to think of the main method as a magical spell or incantation that we have to say in order to get this program to run so we are currently missing a main method but we can easily just type it in so repeat after me public static void main then we need some parentheses string straight braces args and then a set of curly braces and that is it we now have a main method and our program runs and compiles just fine so any code within the main method will execute starting at the top and then work its way down so with the main method any code you place at the top will be executed first so let&#39;s print something to the console window in order to display some text all you have to do is type this system with a capital s dot out dot print then you need a set of parentheses and then a semicolon at the end so within the parentheses of this print method we can type some text to display to the console window but we need to make sure that our text is within a set of double quotes and we can display some text let&#39;s say i don&#39;t know what&#39;s a food you like i love pizza so if i were to run and compile this it&#39;s now going to print i love pizza to the console window let&#39;s say that we would like to display another line of text directly underneath the first we can accomplish that by using another print statement so for convenience i&#39;m going to copy this first line paste it directly underneath and display some other text such as it&#39;s really good so when i compile and run this pay attention the output is one long line of text the reason that this is all displaying as one long line of text is because after printing the first statement our cursor does not move down to the next line in order to do so we could use a print ln statement short for print line it&#39;s as if we&#39;re hitting enter when we finish outputting our text so let&#39;s try this again using a print ln statement and now each line of text is on its own individual line so that&#39;s what distinguishes a print and print line statement a print line will add a new line character as if you&#39;re hitting enter when you finish outputting your text whereas a print statement does not so that&#39;s the difference between the two an alternative to using a print line statement is that we could stick with the standard print statement and at the end of our text add what is referred to as an escape sequence for a new character now an escape sequence is a character preceded with a backslash and one of a few characters that follows directly afterwards this is an escape sequence for a new line character when we add this escape sequence for a new line it&#39;s as if we&#39;re hitting enter wherever we place this escape sequence so within our string of text for our first line at the end we&#39;re going to add backslash n and this will have the same effect as a print line statement it&#39;s going to display our text and then move the cursor down to the next line as you can see there is no additional change to the output within the console window now what if we reverted our print statements back to print line statements and kept the additional escape sequence in for a new line character well we&#39;re going to have an extra empty line of text because we&#39;re displaying our line of output plus an additional character for a new line and then we&#39;re hitting enter at the end via the print line statement so we&#39;re going to have an additional empty line between these two lines of text if we were to do that so a few other escape sequences that you might be interested in include the following a backslash t will add a tab so let&#39;s precede our text with an escape sequence for a tab which is backslash t so this is if we&#39;re hitting tab before displaying our text and we now have some empty space preceding our line of output if you need to put something within quotes let&#39;s try to do so normally so our compiler is actually going to be confused because we cannot normally add a set of quotes because our text already needs to be surrounded with quotes so if we need to literally display some quotes some double quotes we need to precede our double quotes with an escape sequence so backslash then quotes so this will allow us to literally print some double quotes so we&#39;re going to surround our first line of text with some double quotes now and if you need to display a backslash then you need to use double backslashes because if you use just one your compiler thinks you&#39;re trying to use an escape sequence and that&#39;s how to display a backslash in summary anything preceding with a backslash is the beginning of an escape sequence and there&#39;s one of a multitude of characters that could follow afterwards and depending on the character this has special meaning for your compiler to do something specific now anything that is following two forward slashes is the beginning of a single line comment i could write this is a comment and this line of text is going to be ignored by the compiler so there&#39;s going to be no change to this program with the additional comment anything that is a comment is ignored by the compiler so it&#39;s useful if you need to leave yourself a note or for somebody else that&#39;s looking over your code if you need a multi-line comment that is a forward slash followed by an asterisk and anything up to an asterisk and another forward slash will be the bounds of this comment so i could write on a new line for each word this is a comment and all of this will also be ignored by the compiler so that&#39;s how to write a multi-line comment a forward slash and an asterisk and anything up to another asterisk and forward slash so those are comments alright ladies and gentlemen it&#39;s time for this section on tips and tricks and for my first trick i&#39;m going to change the color scheme of my ide we&#39;re currently using the light theme but i much prefer the dark theme i&#39;m going to be joining the dark side so in order to change the color scheme of your ide go to if you&#39;re using eclipse window preferences under the general tab go to appearance theme and you can change the theme here i will click dark i&#39;m going to select apply okay and then apply and close so the dark theme is great if you want to feel like a pretend elite hacker for my next trick i&#39;m going to change the font color as well as the background color of my console window in order to do so head back to window preferences under run debug go to console and you can change the color schemes here i&#39;m going to change the text color to a bright green click ok as well as the background color to a slightly lighter shade of black that should be good when you&#39;re finished click apply and then apply and close and you may need to run this again to see the changes so that&#39;s how to change the font color as well as the background color of your console window so it&#39;s somewhat tedious to have to write a print line statement correct system dot out dot print line normally that&#39;s a lot to type so a shortcut would be to type sys out then hold control space and your ide will auto generate the rest of this print line statement for you let&#39;s move on to trick number four let&#39;s say that we have hundreds of different print line statements and we need to change the text to print because we made a mistake so there&#39;s a feature where we can replace some text in your program with another so let&#39;s pretend we would like to replace print line with print so go to edit find replace and we can replace some text with something else let&#39;s find each instance of print line and replace this with print then click replace all so that will take care of all that for you let&#39;s move on to some final tips so with spaces spaces don&#39;t make much of a difference within your code for example after this dot and my print portion of this print statement i could add a bunch of spaces for no reason and this would run and compile just fine i&#39;m not sure why you would do that but that&#39;s just to reinforce the point that spaces don&#39;t make much of a difference unless you&#39;re using a space to split up some keywords then you might run into an issue or if you&#39;re adding space to a string well then that&#39;s going to have a noticeable effect so spaces for the most part don&#39;t really matter too much depending on where they are here&#39;s a trick on zooming in or out hold control minus to zoom out or control plus to zoom in or you could go to window editor then zoom in or zoom out within this menu here&#39;s my last tip for you let&#39;s say you accidentally close out of your package explorer or your console window you can easily bring those back by going to window show view and then they are all listed here so i would like to bring back my package explorer as well as my console window alright guys and gals you should be ready to get started with java be sure to check out the full 100 video playlist as well and if you could do me a small tiny favor i would greatly appreciate it if you could help me defeat the youtube algorithm by smashing the like button drop a comment down below and subscribe if you&#39;d like to become a fellow bro hey you yeah i&#39;m talking to you if you learn something new then you can help me help you in three easy steps by smashing that like button drop a comment down below and subscribe if you&#39;d like to become a fellow bro [Music] hey how&#39;s it going everybody it&#39;s your bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys all about variables in java so sit back relax and enjoy the show if you find this video helpful please remember to like comment and subscribe your support will help keep this channel running all right guys and gals let&#39;s talk about variables now a variable is a placeholder for a value and it behaves as the value that it contains do you remember from either elementary school or middle school when we were working with algebra we usually had to solve for some sort of variable like x or y and x or y contained some sort of numeric value and for all intents and purposes this variable behaved exactly as this value well with programming we can perform something similar to that but we are not limited to just numbers we could also store words whole sentences and these things called boolean values which hold either true or false but if we&#39;re going to store a value within a variable we have to list the data type of what we&#39;re planning to store within that variable is it going to be a number a word a boolean so we need to discuss data types there are eight primitive data types and a special reference data type called a string anything that i have noted with a star is particularly important so i would pay special attention to these our first data type is boolean this has a size of one bit so it can only hold two values that being true or false if we&#39;re attempting to sign a boolean value we would type either equals true or equals false something similar would be let&#39;s say we have a light switch program well if the light switch is on we could say that the light switch has a value of true if it&#39;s off it has a value of false so this is binary that&#39;s why it only uses one bit it only needs one bit of memory to function next we have byte this isn&#39;t as important as a few others but with one byte we can hold an integer number between negative 128 to 127 because a byte only has one byte of memory a short has two bytes of memory so can hold a larger number between negative 32 000 and some change to 32 000 and some change so integers integers are important these use 4 bytes of memory and they can store a number to just under 2 billion to just over 2 billion because they use 4 bytes of memory and a long they use eight bytes of memory so they can hold a very large number in fact they can hold a number between just under negative nine quintillion to just over positive nine quintillion now a float they can store a fractional number specifically up to six to seven digits what makes floats different from these data types on the top here is that bytes shorts integers and longs can only store a whole integer they cannot store this decimal portion so if you&#39;re working with a program or a variable that uses a fractional number you&#39;ll need to use either a float or a double and a double has more precision it uses eight bytes of memory and it can store a fractional number up to 15 digits so in comparison with a float this has less precision than a double and for an example i just listed a few of the digits of pi with this example we can only store six to seven digits of pi but with a double we can store up to 15. there is one strange convention with floats if you&#39;re going to assign a value to a variable that&#39;s of the float data type you need to follow the value with the letter f with double variables you actually do not need to do so so that&#39;s one major difference when assigning values between these two now let&#39;s move on to characters pronounced char for short think of charizard this uses two bytes of memory and this will store a single character letter or ascii value an example would be the letter f but a common convention with assigning values to a char variable is that you need to surround this value with a pair of single quotes and our last data type is the string data type the size really varies because these are reference data types they store a sequence of characters like a word or a sentence you could store a single character within a string but chars and strings behave differently because chars are primitive data types and strings are reference data types so let&#39;s distinguish the difference between primitive and reference data types here&#39;s a super quick description between the differences of primitive and reference data types primitive data types there are it and we just discussed them they are boolean by short integer longs all those cool things that we just discussed reference data types like strings well there&#39;s an unlimited amount because they are user defined primitives store data reference data types store an address primitives can only hold one value reference data types could hold more than one value primitives use less memory compared to reference data types which use more memory and primitive data types are faster compared to reference data types which are slower now you&#39;re probably thinking cool story bro but how do we create a variable well i&#39;m glad you asked that question so the first process with creating a variable is that we need to declare the data type of what value that this variable is going to store so come up with a variable name like x and we will precede this variable with the data type of the value that we&#39;re planning to store within this variable and then with all statements we follow this with a semicolon at the end the next step is called assignment we will take our variable and assign it equal to some sort of value of the data type that we declared this variable to be but you could combine steps one and two together and this process is called initialization we would take the data type followed by the variable name and set it equal to some value and then add a semicolon at the end to finish the statement so you can either do this in two steps with declaration and assignment or combine them both together which is initialization how about we create a few variables does that sound good to you guys so let&#39;s begin with creating an integer variable let&#39;s say int x this step is called declaration we are declaring the data type of what value is going to be contained within this variable the second step is called assignment we can assign our variable a value let&#39;s say x equals 123 and this step is called assignment or we could combine both of these steps together and this process is called initialization intex equals 123 and this would be initialization so we can do stuff with this variable it will behave as the value that it contains we could print this to the console window so within a print or print line statement we could print the value of x so make sure you do not write this within quotes right now this will display the value that is contained within x which is 123 because this variable behaves as the value that it contains if you were to surround this with quotes what we are doing now is printing a string literal you can also print text as well as a variable together let&#39;s say we have a sentence a string literal that states my number is and then if we want to do some string concatenation with a variable we would add plus and then the variable name make sure this is not within quotes so this will display the sentence my number is plus our variable and in the console window it states my number is 123. so with integer variables the largest number that you can store within an integer variable is just over 2 billion let&#39;s say we are working with an extremely large number like the amount of student debt that i owe well this number is too large to store it within an integer variable we would probably want to use the long data type and one convention with assigning values to a long variable is that you need to follow this number with a capital l for some reason so we can now work with extremely large numbers so this might be useful if you&#39;re working with numbers like the speed of light or something so we now have a long variable and we can display this value a few of the other data types that we mentioned were bytes and shorts they have a lesser number that they can store so with bytes you can only store up to i believe 127 so we could store like 100 within here and this would be fine but 130 would be a little too much though so we don&#39;t tend to use bytes and shorts too much as a beginner because it&#39;s just way more convenient to work with integers um but you might use longs every once in a while too but as beginners we&#39;re mostly going to be sticking with integers now a double can store a number with a fractional portion with integers we cannot store a decimal portion so if this was 123.01 well we cannot store this decimal portion we can only do so with a float or a double so with a float you would type in float for the data type let&#39;s create a new variable like y float y equals 3.14 and a common convention for assigning numbers well values to float variables is that you have to follow this with f so you can store a number with a decimal portion within a float or a double and then we could display whatever this value is so y is equal to 3.14 but people tend to use doubles more because they have more precision and then you do not need this f at the end so this will store up to 15 digits after the decimal portion so we also have booleans let&#39;s say boolean z equals this holds either true or false and then we can display what value is within this boolean so if we print our variable z this will display false or we could hold true and this will display true but we can&#39;t display anything else besides those two like we cannot hold the word pizza because booleans only hold true or false we have characters char for short char and we don&#39;t necessarily need to come up with a variable that&#39;s only one letter we could have a name or something that&#39;s descriptive for this let&#39;s say we have a variable called symbol char symbol equals and then place a character within single quotes let&#39;s say we want the at sign so we now have a variable called symbol that contains the at sign so if i were to display this variable symbol to the console window it will display the value that is contained within which is the at sign and lastly we have strings so with strings these start with a capital s because they are of the reference data type anything that&#39;s a reference data type begins with a capital letter and let&#39;s say we want to store our name so string is the data type let&#39;s say the variable name is name equals and to store a string it works similar to a string literal we&#39;re going to use a set of double quotes and display or add a bunch of text like my name and then i can now display my name to the console window or i could do some string concatenation too and display the word hello plus my name and within the console window it&#39;s now going to display hello bro so that is everything you need to know to get started with variables in java if you would like a copy of all this code i will post all of this in the comments down below don&#39;t be afraid to smash that like button drop a comment down below and subscribe if you&#39;d like to become a fellow bro how&#39;s it going everybody it&#39;s your bro here hope you&#39;re doing well and in this video I&#39;m going to teach you guys how we can swap two variables using Java let&#39;s get into it if you find this video helpful please remember to Like comment and subscribe your support will help keep this channel running alright well here we got two variables we got variable X which contains water and variable Y which I&#39;m gonna put kool-aid in more specifically black cherry kool-aid so let&#39;s just put this in good enough and let&#39;s mix it perfect so we&#39;re going to create two variables and these are going to be of the string datatype so we&#39;ll have string x equals the word water and string y equals the word kool-aid and then let&#39;s display these with a simple print line statement and within here I&#39;ll just type in X colon space plus the variable X and then let&#39;s do the same thing for y so we&#39;ll change X to Y and let&#39;s display these so X currently has water and Y currently has kool-aid so what happens if we set X to equal Y well we get kool-aid for both x and y okay we&#39;re gonna assign variable Y to variable X shit so yeah it looks like we have kool-aid in both variable X and variable Y let&#39;s try again maybe we can set Y to equal X no we just got water everywhere let&#39;s try this again we&#39;re gonna assign variable X to variable Y this time okay that doesn&#39;t seem to work guys my floor is getting really sticky so it appears that we&#39;re going to have to store one of these values within another variable in order to switch these so one thing though we can do is introduce another variable and let&#39;s call this temp and temp is empty let&#39;s create another string so we&#39;ll create string temp and we can either set this to null or can assign no value at all where we simply just declared temp a variable so what we&#39;re gonna do is actually take X and store X whatever value isn&#39;t here within temp so we&#39;re gonna type temp equals x so now X can be filled with something so we&#39;re going to fill it with variable Y so on our next line we&#39;re going to set X to equal Y then we&#39;re going to take our temp variable and store this within Y and lastly y equals temp breaking news ladies and gentlemen we have switched the contents of X and white with the help of our variable temp now back to you bro thank you for the live update news anchor bro it appears on our end that we have also switched the contents of X and y as well so in conclusion if the programming language you&#39;re using doesn&#39;t have any direct function to switch to variables you could do this manually and you can create another variable such as temp and temp is a temporary value to temporarily store one of these values you can set temp to equal X or you can do this with Y and then set X to equal Y and then Y to equal temp so your assignment for today is to post two variables in the comments down below and the code that you used to swap them and that ladies and gentlemen is how you can swap two variables hey how&#39;s it going everybody it&#39;s you bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys how we can accept some user input in java so sit back relax and enjoy the show make sure you like comment and subscribe one like equals one prayer for the youtube algorithm welcome back ladies and gentlemen i&#39;m going to explain how we can use a scanner to accept some user input the scanner class is found in the java utility package of your library and we need to import that before we can use the scanner so outside of the class at the top of our program this is what we&#39;re going to type import java dot util and the name of the class we would like to import which is scanner then a semicolon now we can use the scanner class to create a scanner object so we&#39;re going to be performing a little bit of object oriented programming we&#39;ll be covering object oriented programming in the later part of the series so don&#39;t worry so repeat after me scanner then we need a name for the scanner let&#39;s call it scanner a lowercase equals new scanner then a set of parentheses and a semicolon within the parentheses we&#39;re going to type system dot in and there we go we have our scanner so we can use the scanner to accept some user input so let&#39;s let the user know that we would like them to type in something maybe a name let&#39;s create a prompt that will ask somebody for their name so within a print line statement we&#39;ll type what is your name and next what we&#39;ll do is take our user input and assign it to a variable perhaps a string variable called name string name equals and now we&#39;re going to use our scanner so we type in the name of the scanner dot and to enter a line of text we&#39;re going to use a certain method of the scanner it is the next line method and when we type in user input we type it into the console window here at the bottom so let&#39;s do something with this name maybe display this within a message system.out.printline hello plus whatever your name is so let&#39;s compile and run this what is your name now our program is currently paused until we type in some user input and then press the enter key when you press enter that&#39;s how you submit some user input into the console window so i&#39;m going to click within my console window and type in something i&#39;m going to type in bro and to submit some user input you press the enter key and it states hello plus my name which is what i entered bro now there&#39;s different types of input that we can accept this time let&#39;s accept only an integer number perhaps we can ask somebody for their age so let&#39;s write a prompt for that system.out.printline how old are you and this time we will declare an integer variable maybe called age int age equals scanner dot next and we are looking for int so we can only accept a whole integer u r plus age plus years old okay let&#39;s try this again what is your name bro how old are you let&#39;s just say that i&#39;m 18. hit enter hello bro you are 18 years old so what happens if we do not enter in a number so let&#39;s try and break this what is your name bro how old are you we&#39;re not going to enter a number this time let&#39;s type in the word pizza and see what happens well we encountered an exception we encountered an input mismatch exception because when our scanner is looking for an integer we typed in a string so we need to make sure that the input type the data type matches in a future lesson we&#39;ll be covering exception handling where we can prevent this very thing from happening but for now since we&#39;re beginners we&#39;ll just have to be sure to type in the correct data type of the input that our program is looking for now there&#39;s one more thing that i want to show you guys this is a common problem if you use next line after next int or anything else that&#39;s not next line so let&#39;s ask somebody for their favorite food this time so let&#39;s add that at the end system.out.printline what is your favorite food then we&#39;ll create a string variable called food string food equals scanner dot next line and we will display this system.out.printline you like plus food all right so here are the questions what is your name bro how old are you 18. now pay attention to this when i press enter when we reached the question on what is your favorite food well our program skipped our user input and continued on with the rest of the code so it states hello bro you are 18 years old but we were not able to input anything for our favorite food here&#39;s the reason why here&#39;s what&#39;s going on let&#39;s pretend that this box is a representation of our scanner and we&#39;re going to use the next line method of our scanner to read a line of text so we type in our name and then press the enter key to submit so this backslash n is an escape sequence for a new line the next line method will read an entire line of text and stop when it reaches a new line character so after we call the next line method our scanner is going to be empty however if we were to call a different method that doesn&#39;t read a new line character such as next ins so we type in our input such as the number 18 and then press the enter key that will add a new line character so our next int method is only going to read this numeric portion of our scanner and then when we submit it well this new line character is still going to be within our scanner and if we were to use our scanner again and call a different method like next line well our next line method thinks that we&#39;re at the end because there&#39;s this new line character within our scanner so we would need some way to clear out that new line one easy fix for this is that after you call the next and method what we could do is call the next line method to clear our scanner so i&#39;m just going to copy this portion and paste it we&#39;re not really going to do anything with that newline character this will just clear the scanner for us so now we should be able to answer all three questions so type in your name what is your name it is bro how old are you let&#39;s say i&#39;m 18. what is your favorite food and you can see that it paused to this time unlike the first time and my favorite food is pizza press enter hello bro you are 18 years old you like pizza well then that is one way in which you can use a scanner to accept some user input scanners are capable of much more you can also use them to read the contents of a file and a few other things but we&#39;ll learn about those in future videos and if you need to use a scanner be sure to include this import at the top import java.util.scanner because the scanner class is found within the utility package and then you&#39;ll need to create a scanner object just by following these steps scanner you can call it scanner equals new scanner well guys and gals that is how scanners work in java before you go i would greatly appreciate it if you could do a favor for me and like this video leave a comment down below and subscribe if you&#39;d like to become a fellow bro how&#39;s it going everybody it&#39;s you bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys about expressions in java so sit back relax and enjoy the show you can become a hero and save our channel by smashing that like button drop a comment down below and subscribe if you&#39;d like to become a fellow bro now an expression is a combination of operands and operators an operand is the values variables numbers or different quantities that you might see in a program and operators they are those arithmetic symbols that you might see such as the plus sign for addition subtraction multiplication division and then modulus so let&#39;s go over a few examples just so that we know how they work let&#39;s say i have an integer variable called friends and i will set this equal to maybe 10. so we can change the value of the friends variable by using an arithmetic expression so let&#39;s say that we make a new friend so we&#39;re going to add one to my variable of friends to increment my variable friends i can just use the plus operator and then add a new operand to my variable friends so if i would like to assign a new value to my friends variable i&#39;m going to type in the name of my variable equals friends plus one because we made a new friend and then i will print the value of friends so our friends variable now contains 11. so we could also subtract take a wild guess as to what&#39;s gonna happen we just lost a friend let&#39;s multiply uh let&#39;s multiply our friends by two and now we have 20 friends and let&#39;s divide we&#39;re going to divide our friends into two and we have five friends now the modulus gives you the remainder of division so we have 10 friends what if we had modulus 3 well that does not divide evenly so we&#39;re going to have a remainder of one friend it&#39;s kind of like in group projects where everybody has to get into a group of three and there&#39;s always somebody that&#39;s left over think of it that way although if our group of friends was divided into groups of 2 there would be no remainder because 10 divided by 2 equals 5 evenly and there is no remainder so that&#39;s all what the modulus is it gives you the remainder of any division that occurs now there is a shorthand to increment a variable by one so normally the long way of writing this out would be type in the name of the variable equals because we&#39;re going to reassign a value friends plus one right well there&#39;s a shorthand way of incrementing this and that is to use the increment operator which is just plus plus and then a semicolon so this will add one to a value and now we have 11 friends if you want to decrement that would be minus minus and now we have nine friends hold up wait a minute before you go i gotta discuss integer division because i forgot to talk about it so if we divide a number by an integer if there is normally a remainder well our program is going to truncate the remainder here&#39;s an example let&#39;s say we have 10 friends and we&#39;re going to divide our friends by three so we&#39;re dividing by a whole integer so our result should be 3.33 repeating right wrong it&#39;s three that&#39;s because with integer division we truncate any decimal portion because we cannot store it one easy fix for that is we can cast our result as a double value or a float as well to cast a value as a different data type to the left hand side of our expression we&#39;re going to list the new data type that we would like to convert this value to so we would like to convert our integer as a double value because we would like to retain that decimal portion of our result however our data type friends is an integer so it cannot store a double data type so we should probably convert this to a double so that we can store this value and now this program will successfully store this decimal portion of our expression well that&#39;s really all you need to know to get started with expressions if you would like a copy of all this i will post this in the comments down below and if i could ask for a favor of you guys just to like this video drop a comment down below and subscribe if you&#39;d like to become a fellow bro hey what&#39;s going on everybody it&#39;s your bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys how we can make a very basic gui application in java so sit back relax and enjoy the show if you find this video helpful please remember to like comment and subscribe your support will help keep this channel running all right guys and gals i&#39;m going to teach you all how to create a very basic gui program gui is an acronym for graphical user interface it&#39;s a visual program that we can see and interact with kind of like this so we&#39;ll be using the j option pane class and be creating a few message dialog boxes before we begin we&#39;ll need an import so outside your class let&#39;s type this import java x dot swing dot j option pin so we will be working with the j option pane class now what we would like to do is type in some user information into a sort of dialog box and we&#39;ll store this as a string variable called name kind of like what we did on the video on user input string name and in order to create an input dialog box we&#39;re going to type the name of the class j option pane dot and there&#39;s a few options what we would like is show input dialog and you can really just pick any of these and we can type in a message so with this message let&#39;s state enter your name and when we run this this is what we have we have the small gui dialog box and we can type in our name and submit it but it currently doesn&#39;t do anything so let&#39;s create another message dialog box that will display our name along with a message so j option pain dot show message dialogue for now you can just type in no comma and then a message let&#39;s say hello plus name and let&#39;s try it so our first dialog box is the show input dialog message and we can type in our name and submit a name and our second box here is a message dialog box this just displays some information such as a string of text and it says hello bro this time let&#39;s ask for an edge and store this value within an integer variable called age int age equals and we can just copy all of this j option pane dot show input dialog and the message will be enter your edge there is one issue though when you use the show input dialog box it&#39;s going to return a string and we&#39;re attempting to assign the string into an integer variable so what we would need to do is convert this to an integer and there is actually a method to do that so what i&#39;m going to do is use the integer wrapper class and use the parseint method and within the parenthesis we&#39;re going to take all of this and copy it within our parseint method and then add a semicolon at the end so this will return a string based on what the user types in and the parseint method will convert it to an integer that we can store it within our integer variable of age and then we can display this so let&#39;s display this with another message dialog box j option pane dot show message dialog null will be the first argument and our message will be u r plus age plus years old and let&#39;s try it enter your name bro press okay hello bro then when we click okay again it&#39;s going to go to our next input dialog box enter your age let&#39;s say that i&#39;m 18 click ok you are 18 years old now let&#39;s try this with a double data type this time let&#39;s create a variable called maybe height this will be a double value and the variable name will be height so since we&#39;re working with double values we&#39;re going to change integer to double double with a capital d dot parse double and the message will be enter your height and our message dialog will be u r height and let&#39;s say this is in centimeters tall so we have to be sure that we&#39;re getting the right data type because when you use the input dialog box it&#39;s going to return a string so if you&#39;re attempting to assign that string to a certain data type you have to convert it to that specific data type so let&#39;s try this enter your name bro okay hello bro what is your age let&#39;s say i&#39;m 18 press okay you&#39;re 18 years old enter your height i don&#39;t know what a good height is 240 centimeters and then click ok you are 240.0 centimeters tall in conclusion ladies and gentlemen what we have made is a very simple graphical user interface for fun this is completely optional at this point but we will be learning more about gooeys later in this playlist so if you would like a copy of all this code i will post all of this in the comments down below and if you could do me a favor down below smash the like button drop a comment and subscribe if you&#39;d like to become a fellow bro how&#39;s it going everybody it&#39;s your bro here hope you&#39;re doing well and in this video i&#39;m going to teach you guys a few useful methods of the math class and at the end of this video we&#39;re going to create a program where we will find the hypotenuse of a triangle so sit back relax and enjoy the show make sure you like comment and subscribe one like equals one prayer for the youtube algorithm alrighty then guys and gals in this video i&#39;m going to demonstrate a few useful methods of the math class to begin we&#39;ll need maybe two numbers let&#39;s say that these will be double variables double x let&#39;s set the sequel to 3.14 and double y we will set this to let&#39;s say negative 10. all right the first useful method is the max method this will find the larger of two numbers so in order to use the max method we&#39;re going to type math with a capital m dot and there&#39;s a few recommendations here what we would like is the max method that is right here so there&#39;s a few to choose from we can compare two integers two long values two floats and two doubles i&#39;m going to compare the values of x and y so i&#39;m going to put these within the parentheses of my max method and then we can either display the result or assign this to a new variable let&#39;s say double z equals math.max and we&#39;ll compare x and y and assign the larger number to variable z and we will display the result system.out.printline z and the larger of these two numbers is in fact x which is 3.14 and there is also a min method which will find the lesser of two values which is variable y which is negative 10. another useful method is the absolute function method it&#39;s just abs like abs six-pack abs and we&#39;ll pass in y and this will display the absolute value of y which is 10. so the absolute value is basically a number without the negative sign i&#39;m not a mathematician so i could be wrong in that definition all right we also have the square root function that is sqrt square root of y i don&#39;t know what the square root of negative 10 is but we&#39;re about to find out uh i don&#39;t know i guess that didn&#39;t work let&#39;s change y to 10. 3.16 blah blah blah blah all right that is the square root function we can also round let&#39;s round x so x rounded is 3.0 on the other hand seal like ceiling this will always round up so 3.4 or 3.14 always rounded up is four and floor will always round down so 3.14 always rounded down is 3.0 here&#39;s a project that we can work on let&#39;s create a program that will find the hypotenuse of a triangle and we will ask the user for side x and side y so to begin let&#39;s declare two variables double x and double y actually i take that back let&#39;s declare double z as well because z will be the result the hypotenuse we&#39;ll also need a scanner to accept some user input scanner scanner equals new scanner within the parentheses we&#39;re going to type system.in we&#39;ll need an import so include this import at the top import java.util.scanner we&#39;ll need a prompt for side x and side y we can do that with a print line statement enter side x i can&#39;t type today and we will store the result within variable x x equals we need some user input scanner dot next double because we would like a double value let&#39;s repeat the process for side y enter side y will store the result within variable y now here&#39;s the tricky part there is a mathematical formula to calculate the hypotenuse given two angles well two sides of a triangle so this is what we&#39;re going to do first we&#39;ll multiply x times x plus y times y then we need to put this within the square root function of the math class math make sure it&#39;s with a capital m dot sqrt and we are going to take all of this and place this within the square root function and we will assign this to our variable of z so z equals math dot square root x times x plus y times y and with a print line statement we can display the hypotenuse is plus z that should be good oh then it&#39;s good practice to close your scanner i always forget to do that although it&#39;s not necessary scanner.close all right let&#39;s test this enter side x that is four enter side y let&#39;s say five the hypotenuse is six point four add some change all right so that&#39;s just a simple program that you can make using a function of the math class so if you would like a copy of this code i will post this in the comments down below but yeah that&#39;s a few useful methods of the math class oh and i forgot to tell you guys like comment and subscribe how&#39;s it going everybody to bro hope you&#39;re doing well and in this video i&#39;m going to teach you guys how we can generate some random values in java so sit back relax and enjoy the show you can become a hero and save our channel by smashing that like button drop a comment down below and subscribe if you&#39;d like to become a fellow bro all right welcome back ladies and gentlemen in this video we&#39;re going to be generating some random values some random integers doubles and boolean values so if you&#39;re interested in game design at all this video is a must for you so in order to use random values we should probably import the random class bond within the library so outside of the class this is where we&#39;re going to type we&#39;re going to import java dot util dot random semicolon and now we have access to the random class and that provides us a few options we need an instance of the random class for us to use within the main method we&#39;re going to create an instance of the random class by typing random with a capital r it&#39;s the same name as the class random we need a name for this instance let&#39;s call it random all lower case kind of like what we did with that video on scanners random random equals new random that&#39;s kind of random then a set of parenthesis then a semicolon we now have access to this random instance to generate some random values for us but there&#39;s a disclaimer here these are not true random numbers but something called pseudorandom numbers which are pretty darn close so i just wanted to give you that disclaimer before we got started so you don&#39;t call me a liar let&#39;s generate a random integer and store this within an integer variable like into x into x equals and to generate a random integer we&#39;re going to type the name of our random instance random dot next and there&#39;s also a few others like next boolean next double next float i&#39;ll get to those later what we would like for now is next int and then we will display the result with a print line statement we will display the value of x so the results are on a scale between i would say just under negative 2 billion to just over positive 2 billion so you&#39;ll probably want to limit that let&#39;s pretend that we&#39;re going to roll a six sided dice so to limit the scale or the size of the random number that will generate we can pass in a value to our next int method so within the parentheses of our next int method we&#39;ll limit the size of the integer that&#39;s going to generate if we would like a six-sided dice we&#39;re going to place six here but there&#39;s one catch with this though this will generate a random number between zero and five because computers always start with zero and let&#39;s see if i can roll a zero nope there we go all right so one way to solve this is that if we want the numbers one through six we can just add one so now we&#39;ll get a random number between one and six just like that this time let&#39;s generate a random double value for now i&#39;ll turn this line into a comment and let&#39;s create a new variable called double y double y equals random dot next where is it double and we will display the value of y next double is going to give us a random value between zero and one so this probably has some uses for something what that is i&#39;m not really sure but hey you know you can do this now let&#39;s also generate a random boolean value so boolean z equals random dot next boolean and we will display the value of z so this is going to give us either true or false well everybody that&#39;s how we can use the random class to generate some pseudo-random values for us if you would like a copy of this code i will post this in the comments down below but yeah that&#39;s a few uses of the random class also be sure to leave a like drop a random comment down below and subscribe if you&#39;d like to become a fellow bro

how&amp;#39;s it going everybody it&amp;#39;s bro hope
you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you
guys everything you need to know to get started with java so
sit back relax and enjoy the show if you wouldn&amp;#39;t mind please like comment
and subscribe one like equals one prayer for the
youtube algorithm here&amp;#39;s an outline of the topics covered
in this video if you would like to skip ahead to a certain section
feel free to click on any of the timestamps posted in the description
also at the end of this video we&amp;#39;re going to be discussing some tips and
tricks so be sure to watch until the very end
i&amp;#39;ll give you three reasons why you need to learn java besides being one of the
top three most popular programming languages worldwide
java is an extremely flexible language it&amp;#39;s used extensively by
business enterprises android apps games and if you learn java you could land a
job as a java developer according to glassdoor entry-level java
developers have an average starting salary
of 70 000 that&amp;#39;s nothing to sneeze at so why not learn java are you still here
okay cool let&amp;#39;s begin with the basics computer
languages are on a spectrum between being high level
and low level computers only understand binary it&amp;#39;s referred to as machine code
it&amp;#39;s a low level format that a machine can understand
however humans have difficulty reading binary since it&amp;#39;s all ones and zeros
to create machine code we write in a format called source code
which is understandable by humans and compile
to machine code when we create javasource code the file ends with a
dot java file extension think of compiling code as
transforming source code to machine code we do this because machines can&amp;#39;t read
source code and vice versa humans have trouble reading machine code
unless you&amp;#39;re a robot or an android or something
however when we compile our source code to machine code it&amp;#39;s
machine specific if we write source code and compile on a mac
we can only run that code on a mac and the same concept
applies for pcs although the java language has a solution for this problem
with java we have an intermediary step where we can compile our source code to
a format called bytecode bytecode is cross platform and
ends with a dot class file extension here&amp;#39;s an
example of java source code and here&amp;#39;s an example of that same
source code after we compile it to bytecode
it&amp;#39;s kind of funky right since bytecode is cross-platform you could write your
code on a mac and then send your bytecode file to your
friend who can then run it on their pc using a jvm to translate the bytecode
to machine code but we are going to need the help of a jvm to translate bytecode
to machine code but where can we get a jvm well it&amp;#39;s included with a
jdk and what is a jdk well jdk is an acronym for java development
kit it contains developers tools to help us
code as well as a jre a java runtime environment which
contains a library toolkits and our jvm which is another
acronym for java virtual machine which
translates by code for us to machine code so all you need to worry
about is downloading a jdk and everything else
will be included and now that we know what a jdk is it&amp;#39;s
time to download one so open up the internet and go to
any search engine and look this up java jdk download
go to the first link java se downloads sc stands for
standard edition go to jdk download scroll down and find the
appropriate file for your operating system since i&amp;#39;m
running windows i&amp;#39;m going to download this exe version agree to whatever and download
and when this finishes downloading i&amp;#39;m going to open this
open when done on my computer i currently have a jdk
already installed but i&amp;#39;m going to go ahead and reinstall it for the sake of
this video click next next then wait a little bit
and close i would also recommend an ide that&amp;#39;s another acronym and it
stands for integrated development environment think
of it as software that helps us write other software
you could write code with a text editor such as notepad
and then compile the text file but doing so is not really beginner friendly
so an ide provides an interface for us to write code
check for errors compile and run code there&amp;#39;s two ides that i would recommend
they are both eclipse or intellij idea it doesn&amp;#39;t matter which one you download
because the code that we write is still the same
so let&amp;#39;s download an ide now it&amp;#39;s time to install the
ide i would recommend either the eclipse ide
or intellij idea i&amp;#39;m more comfortable with eclipse so i&amp;#39;m going to stick with
the clips so go back to the interwebs and look up
either eclipse ide or intellij idea ide
so i&amp;#39;m going to look up the clips click the first link
click this orange download button go to download packages and select eclipse ide
for java developers and select the correct download for your
machine i&amp;#39;m going to select the download for windows
and click download and then just wait a little bit again like usual
for me this is currently a zip file so i need to select this file
and extract all with the newly extracted folder navigate
to this eclipse application so you can select this to launch eclipse
for convenience i&amp;#39;m going to create a desktop shortcut
so for me i&amp;#39;m going to go to where is it send to create desktop shortcut and then
click to launch you can select a workspace i&amp;#39;m going to
use the default and click launch we are now within eclipse and we can
begin a new project we are now ready to rock and roll so
let&amp;#39;s begin by creating our first java program but in order to do so we
need to create a java project if you&amp;#39;re brought to this
welcome screen you can close out of this because it&amp;#39;s
annoying and in order to create a java project
navigate to your package explorer and select create a java project
if you&amp;#39;re missing the package explorer you can go to file
new dropper project and that will take you to the same place
we need a unique name for this java project i will call this
my first program and i will want to configure the jre
the java runtime environment and we downloaded that
with the jdk because the jre is a component
of the jdk so i&amp;#39;m currently using 13. i&amp;#39;m going to change this to 15. that was
the one that i more recently downloaded just now so go to configure
jres and i&amp;#39;m going to click add select standard vm vm is virtual machine
click next go to jre home go to directory and i&amp;#39;m going to make
sure that i&amp;#39;m selecting the most recent jdk for me that is 15
select folder finish apply apply and close then finish
if this window pops up you can select don&amp;#39;t create that&amp;#39;s to create a module
if you look to the left hand side within the projects folder we now have a java
project called my first program but we will need to add
what is called a class to this project a class is a
collection of related code so in order to add a
class to this project i&amp;#39;m going to select this project folder
then go to file new class and we need a unique name for this class
i usually call this main but you can name it whatever you want
and then we are going to check this public static
void main checkbox and then click finish with that out of the way take a look
back within your project folder and you should now have
a java file that shares the same name as your class name
my class name is named main therefore my java file is also called main so
this has the dot java file extension and with what we discussed before this
is source code it&amp;#39;s in a format that humans can easily
read and understand and when we compile this source code to
bytecode we&amp;#39;re going to create a new file that
has the dot class file extension and with that
bytecode file we can run that and translate it using a
jvm a java virtual machine here&amp;#39;s our java
file and we have our class and mine is called main so all
the class is is that it&amp;#39;s a collection of related
code we won&amp;#39;t be exploring in depth on the
topic of classes until we reach the subject of
object-oriented programming which is about 20 videos into this playlist
so you have some time so this is our class mine is called main anything
within the outer set of curly braces belongs to the class and is contained
within and within our class we have what is
called a main method our program won&amp;#39;t run without
this method because when we run our code we begin by calling the main method so
if we were to compile and run this code you can do so by clicking the screenplay
button all output is displayed to the console
window and nothing appears to happen because we haven&amp;#39;t written anything yet
so if we were to remove this main method and tried to do this again
we would encounter an error because our main method was not
found in the class main it&amp;#39;s asking us to please define
the main method now looking back when we created our class we went to
file new class and in order to generate the main method we checked this checkbox
here that states public static void main
so the main method generated for us when we created
this class but if we&amp;#39;re missing it we can easily just type it in
a textbook that i read in college said to think of the main method
as a magical spell or incantation that we have to say
in order to get this program to run so we are currently missing a main method
but we can easily just type it in so repeat after me public static
void main then we need some parentheses string straight braces args and then
a set of curly braces and that is it we now have a main method
and our program runs and compiles just fine
so any code within the main method will execute starting at the top
and then work its way down so with the main method
any code you place at the top will be executed first
so let&amp;#39;s print something to the console window in order to display some text
all you have to do is type this system with a capital s dot out
dot print then you need a set of parentheses
and then a semicolon at the end so within the parentheses
of this print method we can type some text to display to the console window
but we need to make sure that our text is within a set of double quotes
and we can display some text let&amp;#39;s say i don&amp;#39;t know what&amp;#39;s a food you like i
love pizza so if i were to run and compile
this it&amp;#39;s now going to print i love pizza to
the console window let&amp;#39;s say that we would like to display
another line of text directly underneath the first we can
accomplish that by using another print statement so for
convenience i&amp;#39;m going to copy this first line
paste it directly underneath and display some other text
such as it&amp;#39;s really good so when i compile and run this pay
attention the output is one long line of text the reason that
this is all displaying as one long line of text is because after
printing the first statement our cursor does not move down to the
next line in order to do so we could use a print
ln statement short for print line it&amp;#39;s as if we&amp;#39;re
hitting enter when we finish outputting our text
so let&amp;#39;s try this again using a print ln statement
and now each line of text is on its own individual line so that&amp;#39;s what
distinguishes a print and print line statement a print line will
add a new line character as if you&amp;#39;re hitting enter when you finish outputting
your text whereas a print statement does not so
that&amp;#39;s the difference between the two an alternative to using a print line
statement is that we could stick with the standard print statement and at the
end of our text add what is referred to as an escape sequence for a new
character now an escape sequence is a character
preceded with a backslash and one of a few characters
that follows directly afterwards this is an escape sequence for a new
line character when we add this escape sequence for a
new line it&amp;#39;s as if we&amp;#39;re hitting enter wherever we place
this escape sequence so within our string of text
for our first line at the end we&amp;#39;re going to add
backslash n and this will have the same effect as
a print line statement it&amp;#39;s going to display our text
and then move the cursor down to the next line as you can see there is no
additional change to the output within the console window
now what if we reverted our print statements back to print line statements
and kept the additional escape sequence in for a new line character
well we&amp;#39;re going to have an extra empty line of text because we&amp;#39;re displaying
our line of output plus an additional character for a
new line and then we&amp;#39;re hitting enter at the end via
the print line statement so we&amp;#39;re going to have an additional empty line between
these two lines of text if we were to do that
so a few other escape sequences that you might be interested in
include the following a backslash t will add a tab
so let&amp;#39;s precede our text with an escape sequence for
a tab which is backslash t so this is if we&amp;#39;re hitting tab before
displaying our text and we now have some empty space
preceding our line of output if you need to put something within
quotes let&amp;#39;s try to do so normally so our compiler is actually going to be
confused because we cannot normally add a set of quotes because our text already
needs to be surrounded with quotes so if we need to literally display some
quotes some double quotes we need to precede
our double quotes with an escape sequence so backslash
then quotes so this will allow us to literally
print some double quotes so we&amp;#39;re going to surround our first line of text
with some double quotes now and if you need to display
a backslash then you need to use double backslashes because if you use
just one your compiler thinks you&amp;#39;re trying to use an escape sequence
and that&amp;#39;s how to display a backslash in summary anything preceding with a
backslash is the beginning of an escape sequence and there&amp;#39;s one of a multitude
of characters that could follow afterwards and
depending on the character this has special meaning for your
compiler to do something specific now anything that is following two
forward slashes is the beginning of a single line
comment i could write this is a comment and this line of text
is going to be ignored by the compiler so there&amp;#39;s going to be
no change to this program with the additional comment
anything that is a comment is ignored by the compiler so it&amp;#39;s useful if you need
to leave yourself a note or for somebody else that&amp;#39;s looking over
your code if you need a multi-line comment
that is a forward slash followed by an asterisk
and anything up to an asterisk and another forward slash
will be the bounds of this comment so i could write
on a new line for each word this is a comment and all of this will also be
ignored by the compiler so that&amp;#39;s how to write a multi-line
comment a forward slash and an asterisk and anything up to another asterisk and
forward slash so those are comments alright ladies and
gentlemen it&amp;#39;s time for this section on tips and tricks and for my first trick
i&amp;#39;m going to change the color scheme of my ide
we&amp;#39;re currently using the light theme but i much prefer the dark theme
i&amp;#39;m going to be joining the dark side so in order to change
the color scheme of your ide go to if you&amp;#39;re using eclipse
window preferences under the general tab go to appearance theme and you can
change the theme here i will click dark i&amp;#39;m going to select
apply okay and then apply and close so the
dark theme is great if you want to feel like a pretend elite hacker for my next
trick i&amp;#39;m going to change the font color as well as the background
color of my console window in order to do so
head back to window preferences under run debug go to console and you
can change the color schemes here i&amp;#39;m going to change the text color to a
bright green click ok as well as the background color
to a slightly lighter shade of black
that should be good when you&amp;#39;re finished click apply
and then apply and close and you may need to run this again to see the
changes so that&amp;#39;s how to change the font color
as well as the background color of your console window so it&amp;#39;s
somewhat tedious to have to write a print line statement correct
system dot out dot print line normally that&amp;#39;s a lot to type
so a shortcut would be to type sys out then hold control space and your ide
will auto generate the rest of this print line statement for you
let&amp;#39;s move on to trick number four let&amp;#39;s say that we have
hundreds of different print line statements and we need to change the
text to print because we made a mistake so
there&amp;#39;s a feature where we can replace some text in your
program with another so let&amp;#39;s pretend we would like to
replace print line with print so go to edit find replace and we can
replace some text with something else let&amp;#39;s find
each instance of print line and replace this with print then click
replace all so that will take care of all that for you
let&amp;#39;s move on to some final tips so with spaces spaces don&amp;#39;t make much of a
difference within your code for example after this dot and my print portion
of this print statement i could add a bunch of spaces
for no reason and this would run and compile just fine
i&amp;#39;m not sure why you would do that but that&amp;#39;s just to reinforce the point that
spaces don&amp;#39;t make much of a difference unless you&amp;#39;re using a space to split up
some keywords then you might run into an issue or if
you&amp;#39;re adding space to a string well then that&amp;#39;s going to have a
noticeable effect so spaces for the most part don&amp;#39;t really matter
too much depending on where they are here&amp;#39;s a trick on zooming in
or out hold control minus to zoom out or control plus
to zoom in or you could go to window editor
then zoom in or zoom out within this menu
here&amp;#39;s my last tip for you let&amp;#39;s say you accidentally close out of your package
explorer or your console window you can easily
bring those back by going to window show view and then they are all
listed here so i would like to bring back my package
explorer as well as my console window alright guys and gals you should be
ready to get started with java be sure to check out the full 100 video playlist
as well and if you could do me a small tiny
favor i would greatly appreciate it if you could help
me defeat the youtube algorithm by smashing the like button drop a comment
down below and subscribe if you&amp;#39;d like to become a
fellow bro hey you yeah i&amp;#39;m talking to you if you
learn something new then you can help me help you in three
easy steps by smashing that like button drop a
comment down below and subscribe if you&amp;#39;d like to become a
fellow bro [Music] hey how&amp;#39;s it going everybody it&amp;#39;s your
bro hope you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys all
about variables in java so sit back relax and enjoy the show if you find this video helpful please
remember to like comment and subscribe your support will
help keep this channel running all right guys and gals let&amp;#39;s talk about
variables now a variable is a placeholder for a
value and it behaves as the value that it
contains do you remember from either elementary school or middle school when
we were working with algebra we usually had to solve for some
sort of variable like x or y and x or y contained
some sort of numeric value and for all intents and purposes
this variable behaved exactly as this value
well with programming we can perform something similar to that
but we are not limited to just numbers we could also store
words whole sentences and these things called boolean values which hold either
true or false but if we&amp;#39;re going to store a
value within a variable we have to list the data type of what
we&amp;#39;re planning to store within that variable is it going to be a number
a word a boolean so we need to discuss data
types there are eight primitive data types and
a special reference data type called a string
anything that i have noted with a star is particularly important
so i would pay special attention to these our first data type
is boolean this has a size of one bit so it can only hold two values that
being true or false if we&amp;#39;re attempting to
sign a boolean value we would type either equals true or
equals false something similar would be let&amp;#39;s say we
have a light switch program well if the light switch is on we could
say that the light switch has a value of true if it&amp;#39;s off
it has a value of false so this is binary that&amp;#39;s why it only uses
one bit it only needs one bit of memory to function
next we have byte this isn&amp;#39;t as important as a few others
but with one byte we can hold an integer number between negative 128 to 127
because a byte only has one byte of memory
a short has two bytes of memory so can hold a
larger number between negative 32 000 and some change
to 32 000 and some change so integers integers are important these use 4 bytes
of memory and they can store a number to just
under 2 billion to just over 2 billion because they use
4 bytes of memory and a long they use eight bytes of memory so they
can hold a very large number in fact they can hold a
number between just under negative nine quintillion to
just over positive nine quintillion now a float
they can store a fractional number specifically
up to six to seven digits what makes floats different from
these data types on the top here is that bytes shorts integers and longs can only
store a whole integer they cannot store this decimal
portion so if you&amp;#39;re working with a program or a
variable that uses a fractional number you&amp;#39;ll
need to use either a float or a double and a double has more
precision it uses eight bytes of memory and it can store a fractional number up
to 15 digits so in comparison with a float this has
less precision than a double and for an example i just
listed a few of the digits of pi with this example we can only store six
to seven digits of pi but with a double we can store up to 15. there is one
strange convention with floats if you&amp;#39;re going to assign a value to a variable
that&amp;#39;s of the float data type you need to follow the value
with the letter f with double variables you actually do not need to do so
so that&amp;#39;s one major difference when assigning values between
these two now let&amp;#39;s move on to characters pronounced
char for short think of charizard this uses two bytes of memory
and this will store a single character letter or ascii value
an example would be the letter f but a common convention with
assigning values to a char variable is that you need to surround
this value with a pair of single quotes and our last data type is the string
data type the size really varies because these are
reference data types they store a sequence of characters
like a word or a sentence you could store a single character within a string
but chars and strings behave differently because
chars are primitive data types and strings are reference data types
so let&amp;#39;s distinguish the difference between primitive and reference data
types here&amp;#39;s a super quick description between
the differences of primitive and reference data types primitive data
types there are it and we just discussed them they are boolean by
short integer longs all those cool things that we just
discussed reference data types like strings well there&amp;#39;s an unlimited
amount because they are user defined primitives store
data reference data types store an address
primitives can only hold one value reference data types could hold more
than one value primitives use less memory compared to
reference data types which use more memory and primitive data
types are faster compared to reference data types
which are slower now you&amp;#39;re probably thinking cool story bro but how do we
create a variable well i&amp;#39;m glad you asked that question so
the first process with creating a variable is that we need to
declare the data type of what value that this
variable is going to store so come up with a variable name like x
and we will precede this variable with the data type of the value that we&amp;#39;re
planning to store within this variable and then with all
statements we follow this with a semicolon at the end the next
step is called assignment we will take our
variable and assign it equal to some sort of value of the data type
that we declared this variable to be but you could combine steps one and two
together and this process is called
initialization we would take the data type followed by
the variable name and set it equal to some value and then add a semicolon at
the end to finish the statement so you can either do this in two steps
with declaration and assignment or combine them both together which is
initialization how about we create a few variables does
that sound good to you guys so let&amp;#39;s begin with creating an
integer variable let&amp;#39;s say int x this step is called declaration we are
declaring the data type of what value is going to be contained
within this variable the second step is called assignment we can assign our
variable a value let&amp;#39;s say x equals 123 and
this step is called assignment or we could combine both of these steps
together and this process is called initialization intex equals 123
and this would be initialization so we can do stuff with this variable it
will behave as the value that it contains
we could print this to the console window so within a print or print line
statement we could print the value of x so make
sure you do not write this within quotes right now this will display the value
that is contained within x which is 123 because this variable
behaves as the value that it contains if you were to surround this with quotes
what we are doing now is printing a string literal
you can also print text as well as a variable together
let&amp;#39;s say we have a sentence a string literal that states
my number is and then if we want to do some string
concatenation with a variable we would add plus and then the variable
name make sure this is not within quotes so this will display the sentence my
number is plus our variable and in the console window it states my
number is 123. so with integer variables the largest number that you can store
within an integer variable is just over 2 billion let&amp;#39;s say we are
working with an extremely large number like the amount of student debt that i
owe well this number is too large to store it within an integer variable
we would probably want to use the long data type
and one convention with assigning values to a long
variable is that you need to follow this number
with a capital l for some reason so we can now work with extremely large
numbers so this might be useful if you&amp;#39;re
working with numbers like the speed of light or something
so we now have a long variable and we can display
this value a few of the other data types that we mentioned were
bytes and shorts they have a lesser number that they can store
so with bytes you can only store up to i believe 127
so we could store like 100 within here and this would be fine but 130 would
be a little too much though so we don&amp;#39;t tend to use bytes and shorts too much as
a beginner because it&amp;#39;s just way more convenient to work with integers
um but you might use longs every once in a while too but
as beginners we&amp;#39;re mostly going to be sticking with integers
now a double can store a number with a fractional portion with integers we
cannot store a decimal portion so if this was 123.01
well we cannot store this decimal portion
we can only do so with a float or a double
so with a float you would type in float for the data type let&amp;#39;s create a new
variable like y float y equals 3.14
and a common convention for assigning numbers
well values to float variables is that you have to follow this
with f so you can store a number with a decimal portion within a
float or a double and then we could display
whatever this value is so y is equal to 3.14
but people tend to use doubles more because they have more precision
and then you do not need this f at the end
so this will store up to 15 digits after the decimal portion
so we also have booleans let&amp;#39;s say boolean
z equals this holds either true or false and then we can display
what value is within this boolean so if we print
our variable z this will display false or we could hold true and this will
display true but we can&amp;#39;t display anything else
besides those two like we cannot hold the word pizza
because booleans only hold true or false we have characters
char for short char and we don&amp;#39;t necessarily need to
come up with a variable that&amp;#39;s only one letter we could have a name or something
that&amp;#39;s descriptive for this let&amp;#39;s say we have a variable called
symbol char symbol equals and then place
a character within single quotes let&amp;#39;s say we
want the at sign so we now have a variable called symbol that contains
the at sign so if i were to display this variable
symbol to the console window it will display the value that is
contained within which is the at sign and lastly we have strings so with
strings these start with a capital s because they are of the reference
data type anything that&amp;#39;s a reference data type begins with a capital letter
and let&amp;#39;s say we want to store our name so string is the data type
let&amp;#39;s say the variable name is name equals
and to store a string it works similar to a string literal
we&amp;#39;re going to use a set of double quotes and display
or add a bunch of text like my name and then i can now display my name to
the console window or i could do some string concatenation
too and display the word hello plus my name
and within the console window it&amp;#39;s now going to display hello
bro so that is everything you need to know to get started with
variables in java if you would like a copy of all this code i will post all of
this in the comments down below don&amp;#39;t be afraid to smash that like
button drop a comment down below and subscribe
if you&amp;#39;d like to become a fellow bro how&amp;#39;s it going everybody it&amp;#39;s your bro
here hope you&amp;#39;re doing well and in this video I&amp;#39;m going to teach you guys how we
can swap two variables using Java let&amp;#39;s get into it if you find this video helpful please
remember to Like comment and subscribe your support will help keep this channel
running alright well here we got two variables we got variable X which
contains water and variable Y which I&amp;#39;m gonna put kool-aid in more specifically
black cherry kool-aid so let&amp;#39;s just put this in good enough and let&amp;#39;s mix it perfect so we&amp;#39;re going to create two
variables and these are going to be of the string datatype so we&amp;#39;ll have string
x equals the word water and string y equals the word kool-aid and then let&amp;#39;s
display these with a simple print line statement and within here I&amp;#39;ll just type
in X colon space plus the variable X and then let&amp;#39;s do the same thing for y so
we&amp;#39;ll change X to Y and let&amp;#39;s display these so X currently has water and Y
currently has kool-aid so what happens if we set X to equal Y well we get
kool-aid for both x and y okay we&amp;#39;re gonna assign variable Y to variable X
shit so yeah it looks like we have kool-aid in both variable X and variable
Y let&amp;#39;s try again maybe we can set Y to equal X no we just got water everywhere
let&amp;#39;s try this again we&amp;#39;re gonna assign variable X to variable Y this time okay
that doesn&amp;#39;t seem to work guys my floor is getting really sticky so it appears
that we&amp;#39;re going to have to store one of these values within another variable in
order to switch these so one thing though we can do is introduce another
variable and let&amp;#39;s call this temp and temp is empty let&amp;#39;s create another
string so we&amp;#39;ll create string temp and we can either set this to null or
can assign no value at all where we simply just declared temp a variable so
what we&amp;#39;re gonna do is actually take X and store X whatever value isn&amp;#39;t here
within temp so we&amp;#39;re gonna type temp equals x so now X can be filled with
something so we&amp;#39;re going to fill it with variable Y so on our next line we&amp;#39;re
going to set X to equal Y then we&amp;#39;re going to take our temp variable and
store this within Y and lastly y equals temp breaking news ladies and gentlemen
we have switched the contents of X and white with the help of our variable temp
now back to you bro thank you for the live update news anchor bro it appears on
our end that we have also switched the contents of X and y as well so in
conclusion if the programming language you&amp;#39;re using doesn&amp;#39;t have any direct
function to switch to variables you could do this manually and you can
create another variable such as temp and temp is a temporary value to temporarily
store one of these values you can set temp to equal X or you can do this with
Y and then set X to equal Y and then Y to equal temp so your assignment for
today is to post two variables in the comments down below and the code that
you used to swap them and that ladies and gentlemen is how you can swap two
variables hey how&amp;#39;s it going everybody it&amp;#39;s you
bro hope you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys how we
can accept some user input in java so sit back relax and enjoy the
show make sure you like comment and subscribe
one like equals one prayer for the youtube algorithm
welcome back ladies and gentlemen i&amp;#39;m going to explain how we can use a
scanner to accept some user input the scanner class is found in the java
utility package of your library and we need to import that before we can use
the scanner so outside of the class at the top of our program
this is what we&amp;#39;re going to type import java dot util and the name of the class
we would like to import which is scanner then a semicolon now we can use the
scanner class to create a scanner object so we&amp;#39;re going to be
performing a little bit of object oriented programming
we&amp;#39;ll be covering object oriented programming in the later part of the
series so don&amp;#39;t worry so repeat after me scanner then we need
a name for the scanner let&amp;#39;s call it scanner a lowercase equals
new scanner then a set of parentheses and a
semicolon within the parentheses we&amp;#39;re going to
type system dot in and there we go we have our scanner so
we can use the scanner to accept some user input
so let&amp;#39;s let the user know that we would like them to type in something
maybe a name let&amp;#39;s create a prompt that will ask somebody for their name
so within a print line statement we&amp;#39;ll type what
is your name and next what we&amp;#39;ll do is take our user
input and assign it to a variable perhaps a string variable
called name string name equals and now we&amp;#39;re going
to use our scanner so we type in the name of the scanner dot and to enter
a line of text we&amp;#39;re going to use a
certain method of the scanner it is the next line method
and when we type in user input we type it into the console window
here at the bottom so let&amp;#39;s do something with this name
maybe display this within a message system.out.printline hello
plus whatever your name is so let&amp;#39;s compile and run this
what is your name now our program is currently paused
until we type in some user input and then press the enter key
when you press enter that&amp;#39;s how you submit some user input into the console
window so i&amp;#39;m going to click within my console
window and type in something i&amp;#39;m going to type in bro and to submit
some user input you press the enter key and it states hello plus my name which
is what i entered bro now there&amp;#39;s different types of input
that we can accept this time let&amp;#39;s accept only an integer
number perhaps we can ask somebody for their age
so let&amp;#39;s write a prompt for that system.out.printline
how old are you and this time we will declare an integer
variable maybe called age int age equals
scanner dot next and we are looking for int
so we can only accept a whole integer u r
plus age plus years old
okay let&amp;#39;s try this again what is your name
bro how old are you let&amp;#39;s just say that i&amp;#39;m
18. hit enter hello bro you are 18 years old so what happens if we
do not enter in a number so let&amp;#39;s try and break this
what is your name bro how old are you we&amp;#39;re not going to
enter a number this time let&amp;#39;s type in the word pizza and see
what happens well we encountered an exception we encountered an input
mismatch exception because when our scanner is
looking for an integer we typed in a string so we need to make
sure that the input type the data type matches in a future
lesson we&amp;#39;ll be covering exception handling where we can prevent
this very thing from happening but for now since we&amp;#39;re beginners we&amp;#39;ll
just have to be sure to type in the correct data type of the input that
our program is looking for now there&amp;#39;s one more
thing that i want to show you guys this is a common problem
if you use next line after next int or anything else that&amp;#39;s not next line so
let&amp;#39;s ask somebody for their favorite food this time
so let&amp;#39;s add that at the end system.out.printline
what is your favorite food then we&amp;#39;ll create a string variable
called food string food equals scanner dot
next line and we will display this system.out.printline you
like plus food all right so here are the questions what
is your name bro how old are you 18. now pay
attention to this when i press enter when we reached the question on
what is your favorite food well our program skipped our user input
and continued on with the rest of the code
so it states hello bro you are 18 years old but we were not able to
input anything for our favorite food here&amp;#39;s the reason why
here&amp;#39;s what&amp;#39;s going on let&amp;#39;s pretend that this box
is a representation of our scanner and we&amp;#39;re going to use the next
line method of our scanner to read a line of text
so we type in our name and then press the enter key to submit
so this backslash n is an escape sequence for a new line
the next line method will read an entire line of text
and stop when it reaches a new line character so
after we call the next line method our scanner is going to be empty
however if we were to call a different method that doesn&amp;#39;t read a new line
character such as next ins so we type in our input such as
the number 18 and then press the enter key that will
add a new line character so our next int method is only going to
read this numeric portion of our scanner and then when we submit it well this new
line character is still going to be within our scanner
and if we were to use our scanner again and call a different method
like next line well our next line method thinks that we&amp;#39;re at the end because
there&amp;#39;s this new line character within our scanner so we would need some way to
clear out that new line one easy fix for this is that after you
call the next and method what we could do is call
the next line method to clear our scanner so i&amp;#39;m
just going to copy this portion and paste it we&amp;#39;re not really
going to do anything with that newline character this will just clear the
scanner for us so now we should be able to answer all
three questions so type in your name what is your name
it is bro how old are you let&amp;#39;s say i&amp;#39;m 18. what
is your favorite food and you can see that it paused to this time
unlike the first time and my favorite food is pizza
press enter hello bro you are 18 years old you like pizza
well then that is one way in which you can use a scanner to accept some user
input scanners are capable of much more you
can also use them to read the contents of a file and a few other
things but we&amp;#39;ll learn about those in future videos
and if you need to use a scanner be sure to include this import at the top
import java.util.scanner because the scanner class is found within the
utility package and then you&amp;#39;ll need to create a scanner
object just by following these steps scanner you can call it scanner equals
new scanner well guys and gals that is how scanners
work in java before you go i would greatly appreciate it if you
could do a favor for me and like this video leave a comment down
below and subscribe if you&amp;#39;d like to become a fellow bro how&amp;#39;s it going everybody it&amp;#39;s you bro
hope you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys about
expressions in java so sit back relax and enjoy the show you can become a hero and save our
channel by smashing that like button drop a comment down below and subscribe
if you&amp;#39;d like to become a fellow bro now an expression is a combination of
operands and operators an operand is the values
variables numbers or different quantities that you might see
in a program and operators they are those
arithmetic symbols that you might see such as the plus sign for addition
subtraction multiplication division and then modulus so let&amp;#39;s go over a few
examples just so that we know how they work let&amp;#39;s
say i have an integer variable called friends and i
will set this equal to maybe 10. so we can change the value of the
friends variable by using an arithmetic expression
so let&amp;#39;s say that we make a new friend so we&amp;#39;re going to add one
to my variable of friends to increment my variable friends i can just use the
plus operator and then add a new operand to
my variable friends so if i would like to assign a new value
to my friends variable i&amp;#39;m going to type in the name of my variable
equals friends plus one because we made a new friend
and then i will print the value of friends so
our friends variable now contains 11. so we could also subtract take a wild
guess as to what&amp;#39;s gonna happen we just lost a friend let&amp;#39;s multiply
uh let&amp;#39;s multiply our friends by two and now we
have 20 friends and let&amp;#39;s divide we&amp;#39;re going to divide our friends into
two and we have five friends now the modulus gives you the remainder
of division so we have 10 friends what if we had
modulus 3 well that does not divide evenly so
we&amp;#39;re going to have a remainder of one friend it&amp;#39;s kind of like in group
projects where everybody has to get into a group of three
and there&amp;#39;s always somebody that&amp;#39;s left over think of it that way
although if our group of friends was divided into groups of 2
there would be no remainder because 10 divided by 2
equals 5 evenly and there is no remainder so that&amp;#39;s all what the modulus
is it gives you the remainder of any division that occurs
now there is a shorthand to increment a variable by one
so normally the long way of writing this out would be type in the name of the
variable equals because we&amp;#39;re going to reassign a
value friends plus one right well there&amp;#39;s a shorthand
way of incrementing this and that is to use the increment
operator which is just plus plus and then a semicolon so this
will add one to a value and now we have 11 friends
if you want to decrement that would be minus minus and now we have nine friends
hold up wait a minute before you go i gotta discuss
integer division because i forgot to talk about it so
if we divide a number by an integer if there is normally a remainder well
our program is going to truncate the remainder
here&amp;#39;s an example let&amp;#39;s say we have 10 friends and we&amp;#39;re going to divide our
friends by three so we&amp;#39;re dividing by a
whole integer so our result should be 3.33 repeating right
wrong it&amp;#39;s three that&amp;#39;s because with integer division
we truncate any decimal portion because we cannot store it one easy fix for that
is we can cast our result as a double value or a float as well
to cast a value as a different data type to the left hand side
of our expression we&amp;#39;re going to list the new data type that we would like to
convert this value to so we would like to convert our integer
as a double value because we would like to
retain that decimal portion of our result
however our data type friends is an integer so
it cannot store a double data type so we should probably convert
this to a double so that we can store this value and now
this program will successfully store this decimal
portion of our expression well that&amp;#39;s really all you need to know
to get started with expressions if you would like a copy of all this i
will post this in the comments down below
and if i could ask for a favor of you guys just to like this video
drop a comment down below and subscribe if you&amp;#39;d like to become a fellow bro hey what&amp;#39;s going on everybody it&amp;#39;s your
bro hope you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys how we
can make a very basic gui application in java so sit back
relax and enjoy the show if you find this video helpful please
remember to like comment and subscribe your support will
help keep this channel running all right guys and gals i&amp;#39;m going to
teach you all how to create a very basic gui program gui is an acronym for
graphical user interface it&amp;#39;s a visual program
that we can see and interact with kind of like this
so we&amp;#39;ll be using the j option pane class and be creating a few message
dialog boxes before we begin we&amp;#39;ll need an import so
outside your class let&amp;#39;s type this import java x dot swing
dot j option pin so we will be working with the j option
pane class now what we would like to do is
type in some user information into a sort of
dialog box and we&amp;#39;ll store this as a string variable called
name kind of like what we did on the video on user input
string name and in order to create an input dialog box we&amp;#39;re going to type
the name of the class j option pane dot and there&amp;#39;s a few options what we
would like is show input dialog and you can really
just pick any of these and we can type in a message so with
this message let&amp;#39;s state enter your
name and when we run this this is what we have we have the small
gui dialog box and we can type in our name and submit it
but it currently doesn&amp;#39;t do anything so let&amp;#39;s create another message dialog box
that will display our name along with a message
so j option pain dot show message
dialogue for now you can just type in no comma and then a message let&amp;#39;s say
hello plus name and let&amp;#39;s try it so our first
dialog box is the show input dialog message
and we can type in our name and submit a name
and our second box here is a message dialog box this just displays some
information such as a string of text and it says
hello bro this time let&amp;#39;s ask for an edge and
store this value within an integer variable called age int
age equals and we can just copy all of this
j option pane dot show input dialog and the message will be enter your edge
there is one issue though when you use the show input dialog box
it&amp;#39;s going to return a string and we&amp;#39;re attempting to assign
the string into an integer variable so what we would need to do is
convert this to an integer and there is actually a
method to do that so what i&amp;#39;m going to do is use the
integer wrapper class and use the parseint
method and within the parenthesis we&amp;#39;re going
to take all of this and copy it within our parseint method
and then add a semicolon at the end so this will return
a string based on what the user types in and the parseint method will convert it
to an integer that we can store it within our integer variable of age
and then we can display this so let&amp;#39;s display this with another
message dialog box j option pane dot show message dialog
null will be the first argument and our message will be
u r plus age plus years old
and let&amp;#39;s try it enter your name bro press okay
hello bro then when we click okay again it&amp;#39;s going to go to our next
input dialog box enter your age let&amp;#39;s say that i&amp;#39;m 18
click ok you are 18 years old now let&amp;#39;s try this with a double data type this time let&amp;#39;s create a variable called
maybe height this will be a double value and the
variable name will be height so since we&amp;#39;re working with double
values we&amp;#39;re going to change integer to double double with a capital d dot parse
double and the message will be enter your height and our message dialog
will be u r height and let&amp;#39;s say this is in centimeters
tall so we have to be sure that we&amp;#39;re getting
the right data type because when you use the input dialog box it&amp;#39;s going to
return a string so if you&amp;#39;re attempting to assign that
string to a certain data type you have to convert it
to that specific data type so let&amp;#39;s try this
enter your name bro okay hello bro what is your age let&amp;#39;s say i&amp;#39;m 18 press
okay you&amp;#39;re 18 years old enter your height i
don&amp;#39;t know what a good height is 240 centimeters and then click ok
you are 240.0 centimeters tall in conclusion ladies and gentlemen what
we have made is a very simple graphical user interface for
fun this is completely optional at this
point but we will be learning more about gooeys later in this playlist
so if you would like a copy of all this code i will post all of this in the
comments down below and if you could do me a favor down
below smash the like button drop a comment and subscribe if you&amp;#39;d
like to become a fellow bro how&amp;#39;s it going everybody it&amp;#39;s your bro
here hope you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys a few
useful methods of the math class and at the end of this video we&amp;#39;re going to
create a program where we will find the hypotenuse of a
triangle so sit back relax and enjoy the show
make sure you like comment and subscribe one like equals one prayer for the
youtube algorithm alrighty then guys and gals in this
video i&amp;#39;m going to demonstrate a few useful methods of the math class to
begin we&amp;#39;ll need maybe two numbers let&amp;#39;s say that these will be double
variables double x let&amp;#39;s set the sequel to 3.14
and double y we will set this to let&amp;#39;s say negative 10. all right the
first useful method is the max method this will find the larger of two numbers
so in order to use the max method we&amp;#39;re going to type math with
a capital m dot and there&amp;#39;s a few recommendations
here what we would like is the max method that is right here so there&amp;#39;s
a few to choose from we can compare two integers two long values two
floats and two doubles i&amp;#39;m going to compare the
values of x and y so i&amp;#39;m going to put these within
the parentheses of my max method and then we can either display
the result or assign this to a new variable let&amp;#39;s say double
z equals math.max and we&amp;#39;ll compare x and y and assign the larger number to
variable z and we will display the result
system.out.printline z and the larger of these two numbers
is in fact x which is 3.14 and there is also a min method which
will find the lesser of two values which is
variable y which is negative 10. another useful
method is the absolute function method it&amp;#39;s
just abs like abs six-pack abs and we&amp;#39;ll pass
in y and this will display the absolute value
of y which is 10. so the absolute value is
basically a number without the negative sign i&amp;#39;m not a mathematician so
i could be wrong in that definition all right we also have the square root
function that is sqrt square root of
y i don&amp;#39;t know what the square root of negative 10 is but we&amp;#39;re about to find
out uh i don&amp;#39;t know i guess that didn&amp;#39;t work
let&amp;#39;s change y to 10. 3.16 blah blah blah blah
all right that is the square root function we can also round
let&amp;#39;s round x so x rounded is 3.0
on the other hand seal like ceiling this will always round up
so 3.4 or 3.14 always rounded up is four and floor will always round
down so 3.14 always rounded down is 3.0
here&amp;#39;s a project that we can work on let&amp;#39;s create a program
that will find the hypotenuse of a triangle
and we will ask the user for side x and side y so to begin let&amp;#39;s declare two
variables double x and double
y actually i take that back let&amp;#39;s declare
double z as well because z will be the result
the hypotenuse we&amp;#39;ll also need a scanner to accept some user input
scanner scanner equals new scanner within the parentheses we&amp;#39;re
going to type system.in we&amp;#39;ll need an import so
include this import at the top import
java.util.scanner we&amp;#39;ll need a prompt for side x and side
y we can do that with a print line
statement enter side x
i can&amp;#39;t type today and we will store the result within
variable x x equals we need some user input
scanner dot next double because we would like a double value
let&amp;#39;s repeat the process for side y enter side y will store the result
within variable y now here&amp;#39;s the tricky part
there is a mathematical formula to calculate the hypotenuse given
two angles well two sides of a triangle so this is what we&amp;#39;re going to do first
we&amp;#39;ll multiply x times x plus
y times y then we need to put this within the square root
function of the math class math make sure it&amp;#39;s with a capital m dot sqrt
and we are going to take all of this and place this within
the square root function and we will assign this to
our variable of z so z equals math
dot square root x times x plus y times y and with a print line statement
we can display the hypotenuse is plus z that should be good
oh then it&amp;#39;s good practice to close your scanner i always forget to do that
although it&amp;#39;s not necessary scanner.close all right let&amp;#39;s test this
enter side x that is four enter side y let&amp;#39;s say five the hypotenuse is
six point four add some change all right so that&amp;#39;s just
a simple program that you can make using a function of the math class
so if you would like a copy of this code i will post this in the comments down
below but yeah that&amp;#39;s a few useful methods of
the math class oh and i forgot to tell you guys like
comment and subscribe how&amp;#39;s it going everybody to bro hope
you&amp;#39;re doing well and in this video i&amp;#39;m going to teach you guys how we can
generate some random values in java so sit back relax
and enjoy the show you can become a hero and save our
channel by smashing that like button drop a comment down below and subscribe
if you&amp;#39;d like to become a fellow bro all right welcome back ladies and
gentlemen in this video we&amp;#39;re going to be generating some random values
some random integers doubles and boolean values
so if you&amp;#39;re interested in game design at all this video is a must for you
so in order to use random values we should probably
import the random class bond within the library
so outside of the class this is where we&amp;#39;re going to type we&amp;#39;re going to
import java dot util dot random semicolon and now we have
access to the random class and that provides us a few options
we need an instance of the random class for us to use
within the main method we&amp;#39;re going to create an instance of the random class
by typing random with a capital r it&amp;#39;s the same name as the class random
we need a name for this instance let&amp;#39;s call it random all lower case kind
of like what we did with that video on scanners
random random equals new random that&amp;#39;s kind of random
then a set of parenthesis then a semicolon we now have access to this
random instance to generate some random values for us
but there&amp;#39;s a disclaimer here these are not true random numbers but something
called pseudorandom numbers which are pretty
darn close so i just wanted to give you that disclaimer before we got started
so you don&amp;#39;t call me a liar let&amp;#39;s generate a random integer
and store this within an integer variable like
into x into x equals and to generate a random integer
we&amp;#39;re going to type the name of our random instance
random dot next and there&amp;#39;s also a few others like next
boolean next double next float i&amp;#39;ll get to those later what
we would like for now is next int and then we will display
the result with a print line statement we will display the value of
x so the results are on a scale between i would say just under
negative 2 billion to just over positive 2 billion so you&amp;#39;ll probably
want to limit that let&amp;#39;s pretend that we&amp;#39;re going to roll a
six sided dice so to limit the scale or the size of the
random number that will generate we can pass in a value to our next
int method so within the parentheses of our next int method
we&amp;#39;ll limit the size of the integer that&amp;#39;s going to generate
if we would like a six-sided dice we&amp;#39;re going to place
six here but there&amp;#39;s one catch with this though
this will generate a random number between zero and five
because computers always start with zero and let&amp;#39;s see if i can roll a zero
nope there we go all right so one way to solve this is that if we want the
numbers one through six we can just add one so
now we&amp;#39;ll get a random number between one and six just like
that this time let&amp;#39;s generate a random double
value for now i&amp;#39;ll turn this line into a
comment and let&amp;#39;s create a new variable called
double y double y equals random
dot next where is it double and we will display
the value of y next double is going to give us
a random value between zero and one so this probably has some uses for
something what that is i&amp;#39;m not really sure but hey
you know you can do this now let&amp;#39;s also generate a random boolean
value so boolean z equals random
dot next boolean and we will display the value of z so
this is going to give us either true or false well everybody that&amp;#39;s how we
can use the random class to generate some
pseudo-random values for us if you would like a copy of this code i will post
this in the comments down below but yeah that&amp;#39;s a few uses of the random
class also be sure to leave a like drop a random comment down
below and subscribe if you&amp;#39;d like to become a
fellow bro

Transcript for:Java Basics Lecture Notes

Transcript for:
Java Basics Lecture Notes