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 use karta hai, Main.java se match karte hue. System.out.println Java ki standard library se aata hai aur use karne ke liye koi import nahi chahiye.

Compiling sabse pehle hoti hai

Jab aap run dabate ho, compiler (javac) ek bhi line run hone 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 run nahi hota — 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 completely ignore kar diya jaata hai, aur yeh sirf isliye hote hain taaki baad mein code padhne wale insaan samajh sakein ki kuch is tarah kyun likha gaya hai.

Khud run karke dekho

Yeh raha ek chhota program jisme ek comment aur do println calls hain. Neeche dikha output actually execute karke nikala gaya hai — text change karke khud bhi example ke neeche button se run karke dekho.

// 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.