Overview
This lecture provides a comprehensive introduction to Java programming, covering installation, programming basics, data types, operators, control structures, arrays, functions, exceptions, and concludes with a simple mini-project.
Setting Up Java
- Download and install the Java Development Kit (JDK) from the official Oracle website for your operating system.
- Download and install an IDE (e.g., IntelliJ IDEA Community Edition) for writing code.
- Create a new Java project and set up your package and class structure as per standard Java conventions.
Java Program Structure
- Java code is organized into classes; every program must have a class and a main method:
public static void main(String[] args).
- The file name must match the public class name.
- Comments in Java are written with
// for single-line and /* ... */ for multi-line.
Data Types and Variables
- Primitive data types: byte, short, int, long, float, double, char, boolean.
- Non-primitive data types: String, arrays, and objects.
- Use
final keyword to declare constants.
- Type casting allows conversion between compatible data types (implicit and explicit casting).
Operators
- Arithmetic operators:
+, -, *, /, %.
- Assignment operator:
=, and compound assignments like +=, -=.
- Increment/Decrement operators:
++, -- (prefix and postfix).
- Comparison operators:
==, !=, >, <, >=, <=.
- Logical operators:
&& (AND), || (OR), ! (NOT).
Input and Output
- Output: Use
System.out.println() and System.out.print().
- Input: Use
Scanner class (Scanner sc = new Scanner(System.in);).
Control Structures
- Conditional statements:
if, else if, else, switch.
- Loops:
for, while, do-while.
- Use
break to exit loops and continue to skip iteration.
Arrays
- Arrays store multiple values of the same type:
int[] arr = new int[3];.
- Access elements via indices, starting at 0.
- Two-dimensional arrays represent matrices:
int[][] matrix = new int[2][3];.
String Methods
- Strings are immutable.
- Common methods:
.length(), .charAt(index), .substring(), .replace(), .concat().
Exception Handling
- Handle exceptions using
try-catch blocks to prevent program crash due to runtime errors.
Functions (Methods)
- Define reusable blocks of code called methods.
- Syntax:
public static void methodName(parameters) { // code }.
- Methods can return values or be void (no return).
Mini-Project Example
- Create a random number guessing game using loops, conditionals, and user input.
Key Terms & Definitions
- JDK (Java Development Kit) — Software package for developing Java applications.
- IDE (Integrated Development Environment) — Application for writing and testing code efficiently.
- Main Method — Entry point of a Java application.
- Primitive Data Type — Basic type such as int, boolean, etc.
- Array — Data structure to store a fixed-size sequence of elements of the same type.
- Type Casting — Changing a variable from one type to another.
- Exception — An error that disrupts program flow, handled with try-catch.
- Method — Reusable code block that performs a specific task.
Action Items / Next Steps
- Practice writing and running simple Java programs.
- Complete the random number guessing mini-project.
- Review array operations, loops, and control structures.
- Prepare questions on any unclear topics for the next lecture.