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In this tutorial, we will learn to write a program in java to reverse an array without using any other array. This array reversal is also known as in place array reversal program in java.

Program 1 : Array Reversal Program in Java without using temp array and variable

• In the below program we are not using any temp array to reverse the array.
• This program is something like reversing the original array.
• Here we are using the concept of swapping the number to reverse the array.

import java.util.*;  
public class Main
{
    public static void main(String[] args) {
        int startIndex,lastIndex;
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the size of array: ");
        int size = sc.nextInt();
        int arr[] = new int[size];
        for(int i=0; i<size; i++) {
            System.out.print("Please give value for index "+ i +" : ");
            arr[i] = sc.nextInt();
        }
        startIndex = 0;
        lastIndex = size - 1;
         while (startIndex < lastIndex)
        {
            arr[startIndex] = arr[startIndex] + arr[lastIndex];
            arr[lastIndex] = arr[startIndex]- arr[lastIndex];
            arr[startIndex] = arr[startIndex]- arr[lastIndex];
            startIndex++;
            lastIndex--;
        }
        System.out.println("Array After Reversing :");
        for(int i=0; i<size; i++)
        {
            System.out.println(arr[i]);
        }
    }
}

Output