# Java Program to Interchange the Diagonals

In this article, we will understand how to interchange the diagonals. The matrix has a row and column arrangement of its elements. A matrix with m rows and n columns can be called as m × n matrix.

Individual entries in the matrix are called element and can be represented by a[i][j] which suggests that the element a is present in the ith row and jth column.

Below is a demonstration of the same −

Suppose our input is

The matrix is defined as:
4 5 6
1 2 3
7 8 9

The desired output would be

The matrix after interchanging the elements:
6 5 4
1 2 3
9 8 7

## Algorithm

Step 1 - START
Step 2 - Declare an integer matrix namely input_matrix, and two integer value namely matrix_size and temp.
Step 3 - Define the values.
Step 4 - Iterate over each element of the matrix using multiple for-loops and swap the required elements of the matrix using a temporary variable.
Step 5 - Display the result
Step 5 - Stop

## Example 1

Here, we bind all the operations together under the ‘main’ function.

public class InterchangeDiagonals {
public static int matrix_size = 3;
public static void main (String[] args) {
int input_matrix[][] = {
{4, 5, 6},
{1, 2, 3},
{7, 8, 9}
};
System.out.println("The matrix is defined as: ");
for (int i = 0; i < matrix_size; i++) {
for (int j = 0; j < matrix_size; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
for (int i = 0; i < matrix_size; ++i)
if (i != matrix_size / 2) {
int temp = input_matrix[i][i];
input_matrix[i][i] = input_matrix[i][matrix_size - i - 1];
input_matrix[i][matrix_size - i - 1] = temp;
}
System.out.println("\nThe matrix after interchanging the elements: ");
for (int i = 0; i < matrix_size; ++i) {
for (int j = 0; j < matrix_size; ++j)
System.out.print(input_matrix[i][j]+" ");
System.out.println();
}
}
}

## Output

The matrix is defined as:
4 5 6
1 2 3
7 8 9

The matrix after interchanging the elements:
6 5 4
1 2 3
9 8 7

## Example 2

Here, we encapsulate the operations into functions exhibiting object-oriented programming.

public class InterchangeDiagonals {
public static int matrix_size = 3;
static void interchange_diagonals(int input_matrix[][]) {
for (int i = 0; i < matrix_size; ++i)
if (i != matrix_size / 2) {
int temp = input_matrix[i][i];
input_matrix[i][i] = input_matrix[i][matrix_size - i - 1];
input_matrix[i][matrix_size - i - 1] = temp;
}
System.out.println("\nThe matrix after interchanging the elements: ");
for (int i = 0; i < matrix_size; ++i) {
for (int j = 0; j < matrix_size; ++j)
System.out.print(input_matrix[i][j]+" ");
System.out.println();
}
}
public static void main (String[] args) {
int input_matrix[][] = {
{4, 5, 6},
{1, 2, 3},
{7, 8, 9}
};
System.out.println("The matrix is defined as: ");
for (int i = 0; i < matrix_size; i++) {
for (int j = 0; j < matrix_size; j++) {
System.out.print(input_matrix[i][j] + " ");
}
System.out.println();
}
interchange_diagonals(input_matrix);
}
}

## Output

The matrix is defined as:
4 5 6
1 2 3
7 8 9

The matrix after interchanging the elements:
6 5 4
1 2 3
9 8 7

Updated on: 29-Mar-2022

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