Keywords and Identifiers in Java

Java mein Keywords kya hote hain?

 ke keywords wo reserved words hote hain jo language ke specific purpose ke liye use hote hain. Inka matlab hota hai ki hum in words ka use variable ya function ke naam ke roop mein nahi kar sakte.

Keywords ka use kyun important hai?

• Java compiler in keywords ko identify karta hai aur unke according code ki meaning samajhta hai.
• Yeh programming rules follow karne ke liye compulsory hote hain.

Java ke Common Keywords ki List:

Keyword Use

class Class define karne ke liye

public Access modifier ke liye

static Static members ke liye

void Method return type define karta hai (jab kuch return nahi hota)

int Integer data type

if Condition check karne ke liye

else Agar if fail ho jaye to alternate block

while Loop chalane ke liye

for Ek aur loop

return Method se value return karne ke liye

new Object create karne ke liye

try, catchException handling ke liye

Note: Java mein total 50 keywords hote hain (as of Java 17), jisme se kuch reserved hote hain future use ke liye.

Identifiers kya hote hain?

Java mein Identifiers wo naam hote hain jo hum variables, methods, classes, objects etc. ke liye dete hain.

Identifier ke Rules:

1. Sirf letters (A-Z, a-z), digits (0-9), underscore (_) aur dollar sign ($) use ho sakte hain.
2. Kisi bhi identifier ka start kabhi bhi number se nahi hona chahiye.
3. Java ke keywords ko identifier ke roop mein use nahi kar sakte.
4. Java identifiers case-sensitive hote hain. (e.g., Name aur name alag alag identifiers hain)

int rollNumber;   // valid identifier
String student_name; // valid identifier
float $amount;    // valid
int 1number;      // invalid (number se start)
int class;        // invalid (class is a keyword)

Memory Trick:

• Keywords – Reserved by Java (Java ke liye fix)
• Identifiers – Hum banaate hain (Apne variable/function/class ke liye)

Conclusion

Agar aap Java seekhna start kar rahe ho to keywords aur identifiers ka clear concept hona bahut zaroori hai. Yeh dono basic cheezein aapko har Java program mein milengi. Inke rules ko follow karke aap error-free aur clean code likh sakte ho.