Aapka Pehla Java Program

Har Java program ko ek class chahiye, aur execution uske andar ek specific method mein shuru hota hai: public static void main(String[] args). Class ka naam file ke naam se match karna chahiye — yeh page hamesha Main istemal karta hai, Main.java se match karte hue. System.out.println Java ki standard library se aata hai aur istemal karne ke liye koi import nahi chahiye.

Compiling sab se pehle hoti hai

Jab aap run dabate hain, compiler (javac) ek bhi line chalne se pehle aapki poori file check karta hai aur use bytecode mein compile karta hai. Agar kahin bhi koi type error ya syntax mistake hai, to kuch bhi nahi chalta — aapko output ke bajaye ek compile error milta hai.

Comments

Comments zyadatar C-family languages ki tarah kaam karte hain: line mein // ke baad jo bhi likha ho use bilkul ignore kar diya jaata hai, aur yeh sirf isliye hote hain taake baad mein code parhne wale log samajh sakein ke kuch is tarah kyun likha gaya hai.

Khud chala kar dekhein

Yeh raha ek chhota program jisme ek comment aur do println calls hain. Neeche dikhaya gaya output waqai execute kar ke nikala gaya hai — text badal kar khud bhi example ke neeche button se chala kar dekhein.

// This is a comment - Java ignores it
public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
        System.out.println("Welcome to Java.");
    }
}

Hello, World!
Welcome to Java.

Aage: variables aur types — primitive types, var type inference, aur String.