List add() Method in Java with Examples

The List add() method adds (appends) an element to a list. It can be used for both ArrayList and LinkedList.

Example of List add() Method:

// Java program to demonstrate
// ArrayList usage
import java.io.*;
import java.util.ArrayList;
import java.util.List;

class GFG {
    public static void main (String[] args) {
        // Create a new ArrayList
        List<String> newList = new ArrayList<>();

        // Add elements to the ArrayList
        newList.add("Hello");
        newList.add("World");

        // Print the ArrayList
        System.out.println(newList);
    }
}

Output:

[Hello, World]

Syntax

The add method has two overloads. It can be used with the index parameter and without the index parameter:

Parameters

• element- Element to be added to the list.
• Index- Index at which element needs to be added.

Returns

It returns true if the specified element is appended and the list changes.

Exceptions

• ClassCastException- When the class of an element prevents it from being added to the list.
• NullPointerException- When the element is Null and the list doesn't allow a null value.
• UnsupportedOperationException- When the list doesn't support add operation.
• IllegalArgumentException- When a property of an element prevents it from being added to a list.

Java List add() Method Examples

Let's look at some examples of how to use the list add() method in Java.

Example 1:

How to add an element to a list in Java using the add(Element E) method:

// Java code to show the implementation of
// add method in list interface
import java.util.*;
public class GfG {

    // Driver code
    public static void main(String[] args)
    {
        List<Integer> l = new ArrayList<>();
        l.add(10);
        l.add(15);
        l.add(20);
        System.out.println(l);
    }
}

[10, 15, 20]

Example 2:

How to add an element at a specific index in a list in Java using the add(int I, Element E) method.

// Java code to show the implementation of
// add method in list interface
import java.util.*;
public class GfG {

    // Driver code
    public static void main(String[] args)
    {
        List<Integer> l = new ArrayList();
        l.add(10);
        l.add(15);
        l.add(1,20);
        System.out.println(l);
    }
}

[10, 20, 15]

Example 3:

How to add an element to a LinkedList in Java using the add() method.

// Java code to show the implementation of
// add method in list interface using LinkedList
import java.util.*;
public class CollectionsDemo {

    // Driver code
    public static void main(String[] args)
    {

        List<Integer> ll = new LinkedList<>();
        ll.add(100);
        ll.add(200);
        ll.add(300);
        ll.add(400);
        ll.add(500);

        System.out.println(ll);
    }
}

[100, 200, 300, 400, 500]

Reference: Official Oracle Docs

Whether you are a beginner starting Java programming or an experienced looking to brush up on your Java skills, this tutorial will provide you with a deep understanding of the add function and its uses in Java.

The add method in Java is a fundamental function for list manipulation. With this guide, you can easily add/append a new element to a list using the add method.

Read More: Java List Methods