Java Add Element to ArrayList

Tags: ArrayList

In this Java core tutorial we learn how to add one element or multiple elements to an java.util.ArrayList in Java programming language.

Table of contents

  1. How to add one element to ArrayList in Java
  2. How to add multiple elements to ArrayList in Java

How to add one element to ArrayList in Java

In Java, with a given ArrayList object we can use the List.add(E e) method to add an element to the ArrayList as the following example Java code.

AddElementToArrayListExample1.java 

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

public class AddElementToArrayListExample1 {
    public static void main(String... args) {
        List<String> list = new ArrayList<>();

        list.add("One");
        list.add("Two");
        list.add("Three");

        System.out.println("ArrayList: " + list);
    }
}
The output as below. 
ArrayList: [One, Two, Three]

How to add multiple elements to ArrayList in Java

In Java, we can use the List.addAll(Collection<? extends E> c) method to add all elements of a collection to another one.

In the following example Java program, we show how to add all elements of an ArrayList object to another ArrayList object using the addAll() method above.

AddElementToArrayListExample2.java 

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

public class AddElementToArrayListExample2 {
    public static void main(String... args) {
        List<String> list1 = new ArrayList<>();
        list1.add("One");
        list1.add("Two");

        List<String> list2 = new ArrayList<>();
        list2.add("Three");
        list2.add("Four");
        list2.add("Five");

        // Add all element from list2 to list1
        list1.addAll(list2);

        System.out.println("list1: " + list1);
        System.out.println("list2: " + list2);
    }
}
The output as below. 
list1: [One, Two, Three, Four, Five]
list2: [Three, Four, Five]

Happy Coding 😊

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