Java Ka Taaruf
Java ek compiled, statically typed, garbage-collected language hai jo directly machine code mein compile nahi hoti — yeh bytecode mein compile hoti hai, jo Java Virtual Machine (JVM) par chalta hai. Yahi Java ke signature promise ka source hai, 'write once, run anywhere': wahi compiled bytecode kisi bhi platform par bina modify kiye chalta hai jahan JVM installed ho.
C++ ke bar-aks, jo aapko raw pointers aur manual memory management deta hai, Java mein koi pointers nahi hain jinhe aap directly manipulate kar sakein aur koi manual delete nahi hai — garbage collector memory ko khud ba khud reclaim kar leta hai jab koi bhi object ko reference nahi karta. Yeh tradeoff Java ko samajhne ke liye central hai: yeh C++ ke low-level control ka kuch hissa memory safety aur simplicity ke liye trade karta hai.
Ek jaldi si jhalak
Yeh raha ek real Java program, jo is page ke apne compiler par waqai chala hai — koi mockup nahi:
public class Main {
public static void main(String[] args) {
String message = "Hello from Java!";
System.out.println(message);
}
}Hello from Java!
Bas itna hi — ek String variable, jo System.out.println se print kiya gaya. Agla lesson aapka pehla poora program chalata hai aur theek se samjhaata hai ke kya ho raha hai.
Practice exercise
Ek variable version naam ka banayein, jiska type int ho aur value 21 ho, phir "Java version: " ke baad version print karein System.out.println ka istemal kar ke.