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Java ArrayList indexOf() Method with Example

ArrayList Class indexOf() method: Here, we are going to learn about the indexOf() method of ArrayList Class with its syntax and example.
Submitted by Preeti Jain, on January 18, 2020

ArrayList Class indexOf() method

  • indexOf() method is available in java.util package.
  • indexOf() method is used to return the index of the first occurrence of the given object.
  • indexOf() method is a non-static method so it is accessible with the class object and if we try to access the method with the class name then we will get an error.


     public int indexOf(Object obj);


  • Object obj – represents the object to search for the index in this Arraylist.

Return value:

The return type of the method is int, it returns the index of the first occurrence of the given object otherwise, it returns -1 when the given object does not exist in this Arraylist.


// Java program to demonstrate the example 
// of int indexOf(int) method of ArrayList.

import java.util.*;

public class IndexOfArrayList {
    public static void main(String[] args) {
        // Create an ArrayList with initial 
        // capacity of storing elements

        ArrayList < String > arr_l = new ArrayList < String > (10);

        // By using add() method is to add 
        // elements in this ArrayList

        // Display ArrayList
        System.out.println("ArrayList Elements :" + arr_l);

        // By using indexOf(Object) method is to
        // return the index of the first occurrence
        // of the given Object in this ArrayList
        int index = arr_l.indexOf("JAVA");

        // Display Index 
        System.out.println("arr_l.indexOf(JAVA) : " + index);


ArrayList Elements :[C, C++, JAVA, DOTNET, PHP]
arr_l.indexOf(JAVA) : 2

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