Java ArrayList add() Method with Examples

The add() method in the ArrayList class is used to add elements to the list. There are different versions of this method.

Example 1: In this example, we will use the add() method to add elements at the end of the list.

// Java Program to demonstrate Addition of
// Elements to an ArrayList
import java.util.*;

public class GFG {
    public static void main(String[] args) {
      
        // Creating an empty ArrayList
        ArrayList<Integer> al = new ArrayList<>();

        // Use add() method to 
        // add elements in the list
        al.add(10);
        al.add(20);
        al.add(30);

        System.out.println("" + al);
    }
}

[10, 20, 30]

Syntax of add(Object element)

public boolean add(Object element)

• Parameters: element: The element to be appended to the list.
• Return Type: boolean: It returns true, if the element was successfully added.

There are two versions of the ArrayList add() method i.e. one without specifying an index and another with a specified index.

The above example and syntax is without specifying an index, now let's see the implementation of the second version below:

Example 2: add(int index, Object element)

This method inserts the specified element at a given position in the ArrayList. It shifts the current element at that position and subsequent elements to the right.

Syntax of add(int index, Object element)

void add(int index, Object element)

Parameters:

• index: The position at which the specified element is to be inserted.
• element: The element to be inserted.

Exception: Throws IndexOutOfBoundsException if the specified index is out of range (index < 0 or index > size()).

Example:

// Java Program to demonstrate
// Addition of elements at a specified index
import java.util.*;

public class GFG {
    public static void main(String[] args) {
      
        // Creating an empty ArrayList
        ArrayList<Integer> al = new ArrayList<>();

        // Use add() method to 
        // add elements in the list
        al.add(10);
        al.add(20);
        al.add(30);
        al.add(40);

        System.out.println("" + al);

        // Adding new element 
        // at index 2
        int i = 2;
        al.add(i, 21);

        System.out.println("" + al);
    }
}

[10, 20, 30, 40]
[10, 20, 21, 30, 40]