Java program to check for Evil Number (ISC Specimen 2016 Question 1)

/**
* The class EvilNumber inputs a number and checks whether it is an Evil Number or not
* @author : www.guideforschool.com
* @Program Type : BlueJ Program - Java
* @ISC Computer Science Practical Specimen Paper - Question 1 
*/
import java.util.*;
class EvilNumber
{
    String toBinary(int n) // Function to convert a number to Binary
    {
        int r;
        String s=""; //variable for storing the result
 
        char dig[]={'0','1'}; //array storing the digits (as characters) in a binary number system
 
        while(n>0)
            {
                r=n%2; //finding remainder by dividing the number by 2
                s=dig[r]+s; //adding the remainder to the result and reversing at the same time
                n=n/2;
            }
        return s;
    }
    
    int countOne(String s) // Function to count no of 1's in binary number
    {
        int c = 0, l = s.length();
        char ch;
        for(int i=0; i<l; i++)
        {
            ch=s.charAt(i);
            if(ch=='1')
            {
                c++;
            }
        }
        return c;
    }
    
    public static void main(String args[])
    {
        EvilNumber ob = new EvilNumber();
        Scanner sc = new Scanner(System.in);
        
        System.out.print("Enter a positive number : ");
        int n = sc.nextInt();
        
        String bin = ob.toBinary(n);
        System.out.println("Binary Equivalent = "+bin);
        
        int x = ob.countOne(bin);
        System.out.println("Number of Ones = "+x);
        
        if(x%2==0)
            System.out.println(n+" is an Evil Number.");
        else
            System.out.println(n+" is Not an Evil Number.");
    }
}