Can You Access? HackerRank Java Solution

Problem:-

You are given a class Solution and an inner class Inner.Private. The main method of class Solution takes an integer  as input. The powerof2 in class Inner.Private checks whether a number is a power of . You have to call the method powerof2 of the class Inner.Private from the main method of the class Solution.

Constraints 

Sample Input

8

Sample Output

8 is power of 2
An instance of class: Solution.Inner.Private has been created

Solution:-

import java.io.*;

import java.lang.reflect.*;

import java.util.*;

import java.util.regex.*;

import java.security.*;

public class Solution {

    public static void main(String[] args) throws Exception {

        DoNotTerminate.forbidExit();    

        try{

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

            int num = Integer.parseInt(br.readLine().trim());

            Object o;// Must be used to hold the reference of the instance of the class Solution.Inner.Private

o = new Inner().new Private();

System.out.println(num + " is " + ((Solution.Inner.Private)o).powerof2(num));

        System.out.println("An instance of class: " + o.getClass().getCanonicalName() + " has been created");

        

        }//end of try

        

        catch (DoNotTerminate.ExitTrappedException e) {

            System.out.println("Unsuccessful Termination!!");

        }

    }//end of main

    static class Inner{

        private class Private{

            private String powerof2(int num){

                return ((num&num-1)==0)?"power of 2":"not a power of 2";

            }

        }

    }//end of Inner

    

}//end of Solution

class DoNotTerminate { //This class prevents exit(0)

    

public static class ExitTrappedException extends SecurityException {

        private static final long serialVersionUID = 1L;

}

public static void forbidExit() {

final SecurityManager securityManager = new SecurityManager() {

@Override

public void checkPermission(Permission permission) {

if (permission.getName().contains("exitVM")) {

throw new ExitTrappedException();

}

}

};

System.setSecurityManager(securityManager);

}

}