How to clone an ArrayList to another ArrayList in Java?

The clone() method of the ArrayList class is used to clone an ArrayList to another ArrayList in Java as it returns a shallow copy of its caller ArrayList. 

Syntax:

public Object clone();

Return Value: This function returns a copy of the instance of Object.

Below program illustrate the Java.util.ArrayList.clone() method:

Example:

Java

// Java program to clone an ArrayList to another ArrayList

import java.util.ArrayList;
public class GFG {

    public static void main(String a[])
    {

        // create ArrayList
        ArrayList<String> ArrList1
            = new ArrayList<String>();

        // Insert elements in ArrayList
        ArrList1.add("Mukul");
        ArrList1.add("Rahul");
        ArrList1.add("Suraj");
        ArrList1.add("Mayank");

        // print ArrayList1
        System.out.println("Original ArrayList = "
                           + ArrList1);

        // clone ArrayList
        ArrayList ArrList2
            = (ArrayList)ArrList1.clone();

        // print ArrayList2
        System.out.println("Clone ArrayList2 = "
                           + ArrList2);
    }
}

Output

Original ArrayList = [Mukul, Rahul, Suraj, Mayank]
Clone ArrayList2 = [Mukul, Rahul, Suraj, Mayank]

Time complexity: O(N) where N is the size of ArrayList

Auxiliary Space: O(N)

Example 2:

Java

// Java code to illustrate clone() method

import java.io.*;
import java.util.*;

public class ArrayListDemo {

    public static void main(String args[])
    {

        // Creating an empty ArrayList
        ArrayList<Integer> list = new ArrayList<Integer>();

        // Use add() method
        // to add elements in the list
        list.add(16);
        list.add(32);
        list.add(48);

        // Displaying the list
        System.out.println("First ArrayList: " + list);

        // Creating another linked list and copying
        // creates a shallow copy
        ArrayList<Integer> sec_list
            = (ArrayList<Integer>)list.clone();

        sec_list.add(64);

        // Displaying the list
        System.out.println("First ArrayList: " + list);

        // Displaying the other linked list
        System.out.println("Second ArrayList is: "
                           + sec_list);
    }
}

Output

First ArrayList: [16, 32, 48]
First ArrayList: [16, 32, 48]
Second ArrayList is: [16, 32, 48, 64]

Time complexity: O(N) where N is the size of ArrayList

Auxiliary Space: O(N)