How do I clone an array variable?

You have an array variable, and you want to make a clone of this array into a new array variable. To do this, you can use Apache Commons Lang ArrayUtils.clone() method. The code snippet below demonstrates the cloning of a primitive array that contains some integer elements in it.

package org.kodejava.commons.lang;

import org.apache.commons.lang3.ArrayUtils;

public class PrimitiveArrayClone {
    public static void main(String[] args) {
        int[] fibonacci = new int[]{1, 1, 2, 3, 5, 8, 13, 21, 34, 55};
        System.out.println("fibonacci = " + ArrayUtils.toString(fibonacci));

        int[] clone = ArrayUtils.clone(fibonacci);
        System.out.println("clone = " + ArrayUtils.toString(clone));

The fibonacci array contents were cloned into the clone array, and we print out the content using ArrayUtils.toString() method.

fibonacci = {1,1,2,3,5,8,13,21,34,55}
clone = {1,1,2,3,5,8,13,21,34,55}

In the code snippet above the clone() method create a reference to a new array. The clone() method itself doesn’t change the original array. In addition to clone primitive arrays, the clone() method also work for cloning an array of objects.

As an example we will create an array of String objects and clone it using the ArrayUtils.clone() method. To display the contents of the array, we will again use the ArrayUtils.toString() method.

package org.kodejava.commons.lang;

import org.apache.commons.lang3.ArrayUtils;

public class ObjectArrayClone {
    public static void main(String[] args) {
        String[] colors = new String[]{"Red", "Green", "Blue", "Yellow"};
        System.out.println("colors = " + ArrayUtils.toString(colors));

        String[] clone = ArrayUtils.clone(colors);
        System.out.println("clone = " + ArrayUtils.toString(clone));

And here is the result:

colors = {Red,Green,Blue,Yellow}
clone = {Red,Green,Blue,Yellow}

The only different between cloning a primitive array and object array using the ArrayUtils.clone() method is that when cloning an object such as String, Date, etc. we need to cast the result of the clone() method into the targeted object type.

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