Java - Copy a List to Another List Example

This post shows you how to copy a List to another List with an example.

Copy a List to Another List Example

A simple way to copy a List is by using the constructor that takes a collection as its argument:

package net.javaguides.examples;

import java.util.ArrayList;
import java.util.List;

/**
 * Different ways to copy a list into another list
 * 
 * @author Ramesh Fadatare
 *
 */
public class CopyListExamples {

    public static void main(String[] args) {

        List < String > fruits = new ArrayList < > ();
        // Adding new elements to the ArrayList
        fruits.add("Banana");
        fruits.add("Apple");
        fruits.add("mango");
        fruits.add("orange");
        System.out.println(fruits);

        // using constructor
        List < String > copyFruits = new ArrayList < > (fruits);
        System.out.println(copyFruits);
    }
}

Output:

[Banana, Apple, mango, orange]
[Banana, Apple, mango, orange]

This approach isn't thread-safe. We may get ConcurrentAccessException error, to fix this problem we may need to use CopyOnWhiteArrayList, in which all mutative operations are implemented by making a fresh copy of the underlying array.

Checkout Copy a List to Another List in Java (5 Ways) - 5 different ways to copy a List to another List with an example.

1. Using Constructor
2. Using addAll() method
3. Using Collections.copy() method
4. Using Java 8
5. Using Java 10

References

https://www.javaguides.net/2020/02/copy-list-to-another-list-in-java-5-ways.html