Java Programming Lecture by Mosh ☕

Introduction to Java Course

• Instructor: Mosh
• Objective: Learn everything needed to get started with Java programming.
• Course Structure:
  • Install necessary tools
  • Learn Java basics
  • Execute Java code
  • Build simple algorithms
  • Professional coding tips
  • Write good code like a professional developer
  • Solid foundation to advance in Java
• Audience: Beginners and anyone interested in learning Java
• Instructor Background:
  • Software Engineer with 20+ years experience
  • Taught over 3 million people
  • Runs a coding school at codewithmosh.com
  • Emphasis on making Java simple and accessible

Installation and Setup

1. Java Development Kit (JDK):
   • Download: Search for JDK download on Oracle website
   • Installation:
     • Accept license agreement
     • Download respective file for your OS (dmg for Mac, etc.)
     • Open installation wizard, continue, and install
     • Delete installation file after completion
2. Code Editor Options:
   • Popular Editors: NetBeans, Eclipse, IntelliJ
   • Recommendation: IntelliJ (community edition is free and sufficient)
   • Installation: Download and drag to Applications folder

Anatomy of a Java Program

• Basic Building Blocks: Functions
  • Perform tasks (e.g., send emails, convert weights)
  • Defined with return type, function name, parameters (optional), and curly braces
• Main Method: Entry point of a Java Program
• Classes: Containers for related functions (methods)
  • Define with class keyword followed by class name and curly braces
  • Methods are functions belonging to a class
• Access Modifiers: Public, private, etc.
  • Determines accessibility of classes and methods
  • Commonly used: public
• Naming Conventions:
  • Classes: Pascal case (each word starts with uppercase)
  • Methods: Camel case (each word starts with uppercase except the first)

Creating a Java Project

1. Open IntelliJ IDEA: Create a new project
2. Select Java SDK: Ensure it is not blank
3. Create Project from Template: Choose command line application
4. Project Naming and Structure: Selection and definition
   • Project name: e.g., Hello World
   • Base package convention (domain name in reverse)
5. File Structure: Project panel, source code inside src folder, base package, and main.java file
6. Code Execution Process:
   • Write and execute first Java program
   • Print output to terminal (e.g., Hello World)

Java Code Execution

• Steps: Compilation and execution
• Compilation: Convert Java code to bytecode using Java compiler
• Execution: bytecode is executed by Java Virtual Machine (JVM)
  • JVM translates bytecode to OS-specific native code
• Platform Independence: Write code once, run anywhere with JVM
• Command Line Usage: Compile with javac, run with java

Interesting Facts about Java

• Developed by James Gosling in 1995 at Sun Microsystems
• Originally named Oak, then Green, finally Java (from Java coffee)
• Four editions of Java: Standard, Enterprise, Micro, and Java Card
• Latest version: Java SE 12 (released March 2019)
• Popularity and usage: 9 million developers, billions of devices
• Average salary of a Java developer: $100,000+ per year in the US

Course Structure Overview

• Parts:
  1. Fundamentals of Programming
  2. Object-Oriented Programming
  3. Core Java APIs
  4. Advanced Features (e.g., streams, threads, database programming)
• First Part: Basics of Java
  • Variables, constants, primitive/reference types
  • Control flow statements
  • Clean coding techniques
  • Error handling and deployment
• Second Part: Object-oriented programming
• Third Part: Core Java APIs
• Fourth Part: Advanced Java features

Variables and Constants

• Variables: Temporary storage in memory
• Types: Customary int, String, boolean, etc.
• Initialization: Before use, give an initial value (e.g., int age = 30;)
• Cosmetics: Naming and readability (use of underscores, meaningful names)
• Operations: Incrementing, copying values
• Constants: Fixed values (e.g., final float PI = 3.14;)

Primitive and Reference Types

• Primitive Types: Byte, short, int, long, float, double, char, boolean
• Reference Types: Used for complex objects (e.g., Date class)
• Memory Management: Reference types hold addresses, primitive types store values

Type Conversion and Casting

• Implicit Casting: Automatic, no data loss
• Explicit Casting: Manual, risk of data loss (e.g., double x = 1.1; int y = (int)x;)
• Wrapper Classes: Parsing strings to numbers (e.g., Integer.parseInt())

Math Class

• Operations: Rounding, ceiling, flooring, min, max, random

String Manipulation

• String Methods: substring, trim, replace, indexOf, length, etc.
• Escape Sequences: Newline (\n), tab (\t), backslash (\\), double quote (\")

Arrays

• Declaration and Initialization: int[] numbers = new int[5];
• Multi-dimensional Arrays: Use curly braces or loops for initialization
• Fixed Length: Arrays have fixed size once initiated

Control Flow Statements

• Comparison Operators: ==, !=, >, <, >=, <=
• Logical Operators: &&, ||, !
• Conditional Statements: if, else if, else, switch
• Ternary Operator: condition ? value1 : value2;
• Loops: for, while, do-while, for-each
• Break and Continue Statements: Terminating or skipping loop iterations

Building Projects and Error Handling

• Project: Create a mortgage calculator using Java
• Input Validation: Use conditional statements to validate user inputs
• Error Handling: Use loops and if-statements to handle invalid inputs

Summary

• Fundamentals of variables, types, and control flow
• Clean coding practices
• Enhanced loop control and error handling
• Preparation for advanced Java programming