Java Introduction

☕ What is Java?

Java is a high-level, object-oriented programming language developed by Sun Microsystems. It's platform-independent, secure, and widely used for enterprise applications, mobile development, and web services.


// Simple Java class example
public class Welcome {
    public static void main(String[] args) {
        System.out.println("Welcome to Java Programming!");
    }
}

Output:

Welcome to Java Programming!

Java History

📅

1995

Java was created by James Gosling

// Originally called "Oak"

🏢

Sun Microsystems

Developed by Sun, now owned by Oracle

// "Write Once, Run Anywhere"

🌟

Evolving

Regular updates and improvements

// Java 8, 11, 17, 21...

🔹 Java Characteristics

Key features that make Java powerful:

🔸 Simple and Familiar

Java syntax is similar to C++ but simpler and cleaner.

// Easy to read and write
int age = 25;
String name = "John";
System.out.println("Hello " + name);

🔸 Object-Oriented

Everything in Java is an object (except primitives).

// Class and object example
class Student {
    String name;
    int age;
}

🔸 Platform Independent

Java bytecode runs on any system with JVM.

// Compile once: javac Program.java
// Run anywhere: java Program

🔹 Java Virtual Machine (JVM)

The JVM makes Java platform-independent:

// Java Source Code (.java)
public class Example {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}

// ↓ Compiled to Bytecode (.class)
// ↓ JVM interprets bytecode
// ↓ Runs on any operating system

Process:

1. Write Java code (.java file)

2. Compile to bytecode (.class file)

3. JVM executes bytecode

4. Program runs on any platform

🔹 Java Editions

Java comes in different editions for different purposes:

☕ Java SE

Standard Edition

Core Java for desktop applications

// Basic Java programming

🌐 Java EE

Enterprise Edition

For web and enterprise applications

// Servlets, JSP, EJB

📱 Java ME

Micro Edition

For mobile and embedded devices

// Mobile applications