Reverse an array without using another array in java

Let’s learn to reverse an array without using another array in java.

Reverse an array without using another array in java

To reverse an array without using another array we are using for loop which loops till middle index of given array and then swap first number with the last number, swap second number with second last number until middle of the given array. Here’s the java program.

import java.util.Arrays;
public class ReverseWithoutArray
{
   public int[] arrayReverse(int[] arrInput)
   {
      if(arrInput == null || arrInput.length <= 1)
      {
         System.out.println("Please enter valid array");
      }
      for(int a = 0; a < arrInput.length / 2; a++)
      {
         int temp = arrInput[a];
         arrInput[a] = arrInput[arrInput.length - 1 - a];
         arrInput[arrInput.length - 1 - a] = temp;
      }
      return arrInput;
   }
   public static void main(String[] args)
   {
      ReverseWithoutArray obj = new ReverseWithoutArray();
      int[] arr = {2, 4, 6, 8, 10, 12, 14, 16};
      System.out.println("Given array: " + Arrays.toString(arr));
      System.out.println("Reversed array: " + Arrays.toString(obj.arrayReverse(arr)));
   }
}


Output:

Given array: [2, 4, 6, 8, 10, 12, 14, 16]
Reversed array: [16, 14, 12, 10, 8, 6, 4, 2]


Also read – ArrayList in java