Nested Loops And Labeled Loops in Java.

Introduction

Kabhi-kabhi hume ek loop ke andar doosri loop chalani padti hai, ya fir loop ke kisi specific level se break ya continue karna hota hai. Nested Loops aur Labeled Loops aise hi cases mein kaafi useful hoti hain.

1. Nested Loops

Kya hote hain?

Jab ek loop ke andar doosri loop hoti hai, use Nested Loop kehte hain.

Syntax:

for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 2; j++) {
        // inner loop
    }
}

Example:

for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 2; j++) {
        System.out.println("i = " + i + ", j = " + j);
    }
}

Output:

i = 1, j = 1  
i = 1, j = 2  
i = 2, j = 1  
i = 2, j = 2  
i = 3, j = 1  
i = 3, j = 2  

Real-life Use:

• Pattern printing
• Matrix traversal (2D arrays)
• Table generation (e.g. multiplication table)

2. Labeled Loops

Kya hote hain?

Labeled loops ka use tab hota hai jab aap nested loops ki kisi particular loop (jaise outer loop) ko break ya continue karna chahte ho.

Syntax:

labelName:
for (...) {
    for (...) {
        if (condition) {
            break labelName; // ya continue labelName;
        }
    }
}

Example with break:

outer:
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        if (i == 2 && j == 2) {
            break outer; // outer loop break ho jayega
        }
        System.out.println("i = " + i + ", j = " + j);
    }
}

Output:

i = 1, j = 1  
i = 1, j = 2  
i = 1, j = 3  
i = 2, j = 1  

Example with continue:

outer:
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        if (j == 2) {
            continue outer; // next iteration of outer loop
        }
        System.out.println("i = " + i + ", j = " + j);
    }
}

Output:

i = 1, j = 1  
i = 2, j = 1  
i = 3, j = 1  

Conclusion

Nested Loops: Loop ke andar loop, commonly used for 2D data

Labeled Loops: Control directly kisi specific loop par dena using labels

Tip: Labeled loops ka use tabhi karein jab logic complex ho. Simple cases mein avoid karein readability ke liye.