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In this post, you will find the solution for Java Instanceof keyword-HackerRank Problem. We are providing the correct and tested solutions of coding problems present on HackerRank. If you are not able to solve any problem, then you can take help from our Blog/website.

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Link for the Problem – Java Instanceof keyword – Hacker Rank Solution

Java Instanceof keyword – Hacker Rank Solution

Problem :

The Java instanceof operator is used to test if the object or instance is an instanceof the specified type.

In this problem we have given you three classes in the editor:

• Student class
• Rockstar class
• Hacker class

In the main method, we populated an ArrayList with several instances of these classes. count method calculates how many instances of each type is present in the ArrayList. The code prints three integers, the number of instance of Student class, the number of instance of Rockstar class, the number of instance of Hacker class.

But some lines of the code are missing, and you have to fix it by modifying only  lines! Don’t add, delete or modify any extra line.

To restore the original code in the editor, click on the top left icon in the editor and create a new buffer.

Sample Input

5
Student
Student
Rockstar
Student
Hacker

Sample Output

3 1 1

Java Instanceof keyword – Hacker Rank Solution

import java.util.*;


class Student{}
class Rockstar{   }
class Hacker{}


public class InstanceOFTutorial{

   static String count(ArrayList mylist){
      int a = 0,b = 0,c = 0;
      for(int i = 0; i < mylist.size(); i++){
         Object element=mylist.get(i);
         if(element instanceof Student)
            a++;
         if(element instanceof Rockstar)
            b++;
         if(element instanceof Hacker)
            c++;
      }
      String ret = Integer.toString(a)+" "+ Integer.toString(b)+" "+ Integer.toString(c);
      return ret;
   }

   public static void main(String []args){
      ArrayList mylist = new ArrayList();
      Scanner sc = new Scanner(System.in);
      int t = sc.nextInt();
      for(int i=0; i<t; i++){
         String s=sc.next();
         if(s.equals("Student"))mylist.add(new Student());
         if(s.equals("Rockstar"))mylist.add(new Rockstar());
         if(s.equals("Hacker"))mylist.add(new Hacker());
      }
      System.out.println(count(mylist));
   }
}