? Java Nested Loops

? Quick Overview

Nested loops in Java mean placing one loop inside another loop. The inner loop runs completely for each iteration of the outer loop. Nested loops are commonly used for working with patterns, tables, matrices, and multi-dimensional data.

? Key Concepts

One loop inside another loop
Inner loop executes fully for each outer loop iteration
Used for patterns, grids, tables, and matrices
Works with for, while, and do-while

? Syntax / Theory

The most common nested loop structure is a for loop inside another for loop.

? View Code Example

// General syntax of nested for loop
for(int i=1;i<=rows;i++){
for(int j=1;j<=columns;j++){
System.out.print("* ");
}
System.out.println();
}

? Code Example

Printing a simple square star pattern using nested loops.

? View Code Example

// Java program to print a 5x5 star pattern
class NestedLoops{
public static void main(String[] args){
for(int i=1;i<=5;i++){
for(int j=1;j<=5;j++){
System.out.print("* ");
}
System.out.println();
}
}
}

? Live Output / Explanation

The outer loop controls the number of rows. The inner loop prints stars in each row. After the inner loop finishes, a new line is printed, creating a square pattern.

* * * * *
* * * * *
* * * * *
* * * * *
* * * * *

? Interactive: Pattern Generator

Change the number of rows to simulate the Java logic in real-time!

Loop Size (N):

* * * * * * * * * * * * * * * * * * * * * * * * *

✅ Tips & Best Practices

Keep loop conditions simple and readable
Avoid unnecessary nesting to improve performance
Use meaningful variable names like row and col
Understand loop flow before writing complex logic

? Try It Yourself

Create a right-angle triangle pattern
Print a multiplication table using nested loops
Try nested while loops instead of for
Generate number patterns (1 22 333)