Related Articles
Java Program to Interchange Elements of First and Last in a Matrix Across Rows
• Last Updated : 30 Mar, 2021

For a given 4 × 4 matrix, the task is to interchange the elements of the first and last rows and then return the resultant matrix.

Illustration:

```Input 1:  1  1  5  0
2  3  7  2
8  9  1  3
6  7  8  2
Output 1: 6  7  8  2
2  3  7  2
8  9  1  3
1  1  5  0

Input 2:  7   8   9  10
11  13  14   1
15   7  12  22
11  21  30   1

Output 2: 11  21  30   1
11  13  14   1
15  7   12  22
7   8   9   10```

Approach:

To get the required output, we need to swap the elements of the first and the last row of the stated matrix.

Example

## Java

 `// Java Program to Interchange Elements of First``// and Last Row in a Matrix`` ` `// Importing input output classes``import` `java.io.*;`` ` `// Main Class``public` `class` `GFG {`` ` `    ``// Method 1``    ``// To swap First and Last Row``    ``static` `void` `swap_First_last(``int` `mat[][])``    ``{``        ``int` `rws = mat.length;`` ` `        ``// Interchanging of elements between the``        ``// first and last rows``        ``for` `(``int` `j = ``0``; j < mat[``0``].length; j++) {`` ` `            ``// Using temporary variable so in order``            ``// not to loose the values of the matrix``            ``// Simply, swapping the values stored``            ``int` `temp = mat[``0``][j];``            ``mat[``0``][j] = mat[rws - ``1``][j];``            ``mat[rws - ``1``][j] = temp;``        ``}``    ``}`` ` `    ``// Method 2``    ``// Main driver method``    ``public` `static` `void` `main(String args[])``        ``throws` `IOException``    ``{``        ``// Input integer matrix``        ``int` `mat[][] = { { ``2``, ``3``, ``4``, ``5` `},``                        ``{ ``8``, ``9``, ``6``, ``15` `},``                        ``{ ``13``, ``22``, ``11``, ``18` `},``                        ``{ ``19``, ``1``, ``2``, ``0` `} };`` ` `        ``// Display message only``        ``System.out.println(``"Input matrix is as follows : "``);`` ` `        ``// Printing the Input matrix``        ``for` `(``int` `j = ``0``; j < mat.length; j++) {``            ``for` `(``int` `k = ``0``; k < mat[``0``].length; k++)`` ` `                ``// Print the elements of the input matrix``                ``System.out.print(mat[j][k] + ``" "``);`` ` `            ``// New line as row ended``            ``System.out.println();``        ``}`` ` `        ``System.out.println(``            ``"Swapped matrix is as follows : "``);`` ` `        ``// Calling the (method1) to swap rows in a matrix``        ``swap_First_last(mat);`` ` `        ``// Printing the Swapped matrix``        ``for` `(``int` `j = ``0``; j < mat.length; j++) {``            ``for` `(``int` `k = ``0``; k < mat[``0``].length; k++)`` ` `                ``// Print the elements of the swapped matrix``                ``System.out.print(mat[j][k] + ``" "``);`` ` `            ``// New line as row ended``            ``System.out.println();``        ``}``    ``}``}`
Output:
```Input matrix is as follows :
2 3 4 5
8 9 6 15
13 22 11 18
19 1 2 0
Swapped matrix is as follows :
19 1 2 0
8 9 6 15
13 22 11 18
2 3 4 5
```

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

My Personal Notes arrow_drop_up