Reversing an array.

Here’s a Java program that reverses an array:

  import java.util.Arrays;

  public class ArrayReversal {

    public static void main(String[] args) {

        int[] array = {1, 2, 3, 4, 5};

        System.out.println("Original Array: " + Arrays.toString(array));

        reverseArray(array);    

        System.out.println("Reversed Array: " + Arrays.toString(array));

    }

    public static void reverseArray(int[] arr) {

        int start = 0;

        int end = arr.length - 1;

        while (start < end) {

            // Swap elements at start and end positions

            int temp = arr[start];

            arr[start] = arr[end];

            arr[end] = temp;

            // Move the pointers towards the center

            start++;

            end--;
        }
    }
}

This program defines a method called `reverseArray()` that takes an integer array as input and reverses it by swapping elements from the start and end positions until the pointers meet in the middle. The `main()` method demonstrates the usage of the `reverseArray()` method by creating an array, reversing it, and then printing both the original and reversed arrays.

When you run the program, it will output:

Original Array: [1, 2, 3, 4, 5]

Reversed Array: [5, 4, 3, 2, 1]

The original array `[1, 2, 3, 4, 5]` gets reversed to `[5, 4, 3, 2, 1]`.