Nested Loops

In Java, you can nest loops by placing one loop inside another. This is often used for complex iterations, such as working with two-dimensional arrays or for solving problems that involve nested structures. The most common types of nested loops are nested for loops.

Example of Nested for Loop - Multiplication Table:

public class NestedForLoopExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= 5; j++) {
                System.out.print(i * j + "\t");
            }
            System.out.println(); // Move to the next line after each row
        }
    }
}

In this example:

• The outer loop (for (int i = 1; i <= 5; i++)) iterates over the rows of the table.
• The inner loop (for (int j = 1; j <= 5; j++)) iterates over the columns for each row.
• System.out.print(i * j + "\t"); prints the product of i and j followed by a tab character.
• System.out.println(); moves to the next line after each row is printed.

The output of this program will be a simple multiplication table:

1	2	3	4	5	
2	4	6	8	10	
3	6	9	12	15	
4	8	12	16	20	
5	10	15	20	25

Example of Nested while Loop - Pattern:

public class NestedWhileLoopExample {
    public static void main(String[] args) {
        int i = 1;

        while (i <= 3) {
            int j = 1;
            while (j <= i) {
                System.out.print("* ");
                j++;
            }
            System.out.println();
            i++;
        }
    }
}

In this example, the outer while loop controls the rows, and the inner while loop controls the number of asterisks printed in each row. The output of this program will be:

* 
* * 
* * *

Example of Combination of Loop Types - while Inside for:

public class CombinationOfLoopsExample {
    public static void main(String[] args) {
        int i = 1;

        while (i <= 3) {
            for (int j = 1; j <= i; j++) {
                System.out.print("* ");
            }
            System.out.println();
            i++;
        }
    }
}

This program produces the same output as the nested while loop example.

Nested loops provide a way to handle more complex patterns and structures in your code. However, it's essential to maintain clarity and avoid excessive nesting to keep the code readable.