How to Copy Elements from one ArrayList into Another in Java

In this example, let us see how to copy all elements of one ArrayList object to another in Java.

Source Code

package com.beginner.examples;

import java.util.ArrayList;
import java.util.Collections;

public class CopyElementsToArrayList {

	public static void main(String[] args) {

		ArrayList al = new ArrayList();
		// Add elements
		al.add("A");
		al.add("B");
		al.add("C");

		ArrayList al_copy = new ArrayList();
		// Add elements
		al_copy.add("a");
		al_copy.add("b");
		al_copy.add("c");
		al_copy.add("d");

		System.out.println("Copy the former:"+al_copy);
		
		
		//It overlays the original element
		Collections.copy(al_copy, al);

		System.out.println("Copy after:" + al_copy);

	}

}

Output:

Copy the former:[a, b, c, d]
Copy after:[A, B, C, d]

References

Imported packages in Java documentation:

• ArrayList
• Collections
• Collection