Reverse an Array in Java

We can reverse an array in Java in the following ways:

• Using the Collections.reverse() method
• Using the ArraysUtils.reverse() method
• Using the for-loop

Reverse an array in Java using the Collections.reverse() method

We can use the reverse() method from the Collections class that accepts the Collection. We just need to convert the array to a list first.

Example

public class Test {

  public static void main(String[] args) {

    Integer[] array = new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // reverse an array
    Integer[] reversedArray = reverse(array);

    // print the elements
    Arrays.stream(reversedArray).forEach(item -> System.out.print(item + " "));
  }

  public static Integer[] reverse(Integer[] array) {
    List arrayList = Arrays.asList(array);
    Collections.reverse(arrayList);
    return arrayList.toArray(array);
  }
}

Reverse an array using the ArraysUtils.reverse() method

There is also a reverse() method from the ArrayUtils class that belongs to the Apache Commons library. We need to add the dependency to use this class.

Example

import java.util.*;
import org.apache.commons.lang3.ArrayUtils;

public class Test {

  public static void main(String[] args) {

    Integer[] array = new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // reverse an array
    ArrayUtils.reverse(array);

    // print the elements
    Arrays.stream(array).forEach(item -> System.out.print(item + " "));
  }
}

Reverse an array using the for-loop

We can use the for-loop to reverse an array by swapping the elements, like in the following example:

public class Test {

  public static void main(String[] args) {

    Integer[] array = new Integer[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    // reverse an array
    for (int i = 0, j = array.length - 1; j >= i; i++, j--) {
      int temp = array[i];
      array[i] = array[j];
      array[j] = temp;
    }

    // print the elements
    Arrays.stream(array).forEach(item -> System.out.print(item + " "));
  }
}