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How to copy a list to another list in Java?
A List of elements can be copied to another List using multiple ways.
Way #1
Create a List by passing another list as a constructor argument.
List<String> copyOflist = new ArrayList<>(list);
Create a List and use addAll() method to add all the elements of the source list.
Way #2
List<String> copyOfList = new ArrayList<>(); copyOfList.addAll(list);
Way #3
Use Collections.copy() method to copy the contents of source list to destination. Existing elements will be overridden by indexes if any.
Collections.copy(copyOfList, list);
Way #4
Use Streams to create a copy of a list.
List<String> copyOfList = list.stream().collect(Collectors.toList());
Example
Following is the example to explain the creation of copy of List object using multiple ways −
package com.tutorialspoint;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
public class CollectionsDemo {
public static void main(String[] args) {
List<String> list = Arrays.asList("Zara","Mahnaz","Ayan" );
System.out.println("Source: " + list);
List<String> copyOfList1 = new ArrayList<>(list);
System.out.println("Copy 1: " + copyOfList1);
List<String> copyOfList2 = new ArrayList<>();
copyOfList2.addAll(list);
System.out.println("Copy 2: " + copyOfList2);
List<String> copyOfList3 = Arrays.asList("Rob","Julie","John" );
Collections.copy(copyOfList3, list);
System.out.println("Copy 3: " + copyOfList3);
List<String> copyOfList4 = list.stream().collect(Collectors.toList());
System.out.println("Copy 4: " + copyOfList4);
}
}Output
This will produce the following result −
Source: [Zara, Mahnaz, Ayan] Copy 1: [Zara, Mahnaz, Ayan] Copy 2: [Zara, Mahnaz, Ayan] Copy 3: [Zara, Mahnaz, Ayan] Copy 4: [Zara, Mahnaz, Ayan]
Updated on: 21-Oct-2023
23K+ Views
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