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How To Add An Element To ArrayList In Java?

In this article, we will see how to add an element in ArrayList. Also, we will see how we can add an element at a particular index in ArrayList.

Introduction

We can add an element to the end of ArrayList using the add(E e) method.

To add an element to a particular index, we can use the add(int index, E element) method.

Let’s see these two methods one by one.

1. add(E e)

The method signature for this method is given below.

1

public boolean add(E e)

This method appends the specified element e to the end of the list.

This method returns true if the element is added to the list otherwise, it returns false.

Let’s see a Java program to add an element to the list using the above method.

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import java.util.ArrayList;

/**
 * A Java program to add an element to the list.
 * 
 * The add(E e) method will add an element to 
 * the end of the ArrayList.
 * 
 * @author coderolls.com
 *
 */
public class ArrayListExample {

  public static void main(String[] args) {
  
    ArrayList<String> arrayList = new ArrayList<String>();
    
    //adding elements to the arrayList
    arrayList.add("Gaurav");
    arrayList.add("Shyam");
    
    System.out.println(arrayList);// [Gaurav, Shyam]
    
    // adding an element to  the arrayList
    // element will be added to the end of the arrayList
    arrayList.add("Saurav");
    
    System.out.println(arrayList); // [Gaurav, Shyam, Saurav]
  
  }
}

Output:

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2

[Gaurav, Shyam]
[Gaurav, Shyam, Saurav]

2. add(int index, E element)

The method signature for this method is given below.

1

public boolean add(int index, E element)

This method adds the specified element element at the specified index index.

This method has a return type as void so, it will not return anything.

Below, we will see a Java program to add an element at the specified index in ArrayList.

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import java.util.ArrayList;

/**
 * A Java program to add an element at the specific index.
 * 
 * The add(int index, E element) method will add 
 * an element at the specified index in ArrayList.
 * 
 * @author coderolls.com
 *
 */
public class ArrayListAddExample {

  public static void main(String[] args) {
  
    ArrayList<String> arrayList = new ArrayList<String>();
    
    //adding elements to the arrayList using the normal add method
    arrayList.add("Gaurav");
    arrayList.add("Shyam");
    
    System.out.println(arrayList);// [Gaurav, Shyam]
    
    // adding an element to  the arrayList at index 1
    arrayList.add(1, "Saurav");
    
    System.out.println(arrayList); // [Gaurav, Saurav, Shyam]
  }
}

Output:

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[Gaurav, Shyam]
[Gaurav, Saurav, Shyam]

Conclusion

We can add an element to the ArrayList using the add() method in two ways.

  1. add(E e) - It will add an element to the end of the ArrayList
  2. add(int index, E element)- This method will add an element to the specified index

The example Java programs given in the above tutorial can be found at this GitHub Repository.

If you know of any other ways, you can write a comment below.

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