Home » Java programming language

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.

Syntax:

     public int indexOf(Object obj);

Parameter(s):

  • 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.

Example:

// 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
        arr_l.add("C");
        arr_l.add("C++");
        arr_l.add("JAVA");
        arr_l.add("DOTNET");
        arr_l.add("PHP");

        // 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);
    }
}

Output

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





Comments and Discussions

Ad: Are you a blogger? Join our Blogging forum.





Languages: » C » C++ » C++ STL » Java » Data Structure » C#.Net » Android » Kotlin » SQL
Web Technologies: » PHP » Python » JavaScript » CSS » Ajax » Node.js » Web programming/HTML
Solved programs: » C » C++ » DS » Java » C#
Aptitude que. & ans.: » C » C++ » Java » DBMS
Interview que. & ans.: » C » Embedded C » Java » SEO » HR
CS Subjects: » CS Basics » O.S. » Networks » DBMS » Embedded Systems » Cloud Computing
» Machine learning » CS Organizations » Linux » DOS
More: » Articles » Puzzles » News/Updates


© https://www.includehelp.com some rights reserved.