How to add element to ArrayList with examples

In this post, I will be sharing how to add an element or object to ArrayList. We can easily achieve our goal by using add() method of the java.util.ArrayList class. According to Java docs, the ArrayList add() method appends the element or object to the end of the ArrayList. Given below are the three examples:

1. Using String elements

2. Using Integer elements

3. Using Custom Object

Read Also: How to iterate or loop over ArrayList in Java

Let's dive deep into the topic:

How to add an element to ArrayList in Java

1. Using boolean add(Object element) method

The method signature of add method is:

 public boolean add(Object element)

1.1 Add String elements to the ArrayList Object

In the below example, we will create an empty ArrayList. Then add String elements to it using ArrayList.add() method.

 import java.util.*;
public class AddMethodExample {
    public static void main(String args[]) {
        //Declaration of String ArrayList 
        ArrayList<String> arrlist = new ArrayList<String>(); 
 
        //Example of add method for String ArrayList
        arrlist.add("California");
        arrlist.add("New York");
        arrlist.add("Boston");
        arrlist.add("San jose");
        arrlist.add("San Francisco");
        System.out.println("ArrayList Elements of String Type: "+ arrlist);
    }
}

Output:
ArrayList Elements of String Type: [California, New York, Boston, San jose, San Francisco]

1.2 Add Integer elements to the ArrayList Object

In the below example, we will create an empty ArrayList and then add Integer elements to it using the ArrayList.add() method.

 import java.util.*;
public class AddMethodExample2 {
    public static void main(String args[]) {
        //Declaration of Integer ArrayList
        ArrayList<Integer> arrlist2 = new ArrayList<Integer>(); 
 
        //Example of add method for Integer ArrayList
        arrlist2.add(12);
        arrlist2.add(3);
        arrlist2.add(9);
        arrlist2.add(96);
        arrlist2.add(8);
        System.out.println("ArrayList Elements of Integer Type: "+arrlist2);
    }
}

Output:
ArrayList Elements of Integer Type: [12, 3, 9, 96, 8]

1.3 Add Custom Object to the ArrayList

In the below example, we will create an ArrayList of Mobile objects and add Mobile objects to the list.

 import java.util.*;
public class AddMethodExample3 {
    public static void main(String args[]) {
        //Declaration of ArrayList of Mobile objects
        ArrayList<Mobile> mobiles = new ArrayList<>(); 
 
        //Example of add method for ArrayList of Mobile objects
        mobiles.add(new Mobile("Apple","iPhone"));
        mobiles.add(new Mobile("Samsung","Galaxy S"));
        mobiles.add(new Mobile("Xiaomi","Note Pro"));
        // Displaying Mobile company and model
        for(Mobile mobile: mobiles) {
            mobile.printMobiles();
        }
    }
}
class Mobile {
    public String company;
    public String model;
    // Constructor
    public Mobile(String company, String model) {
        this.company = company;
        this.model = model;
    }
    
    public void printMobiles() {
        System.out.println(company + " produces " + model);
    }
}

Output:
Apple produces iPhone
Samsung produces Galaxy S
Xiaomi produces Note Pro

That's all for today. Please mention in the comments if you have any questions related to how to add an element or object to ArrayList in Java.

Reference:
ArrayList add(E e) method