JavaInterface.java

// https://www.hackerrank.com/challenges/java-interface/problem?h_r=next-challenge&h_v=zen&h_r=next-challenge&h_v=zen&h_r=next-challenge&h_v=zen&h_r=next-challenge&h_v=zen

import java.util.Scanner;

public class JavaInterface {
 public static void main(String[] args) {
 MyCalculator my_calculator = new MyCalculator();
 System.out.print("I implemented: ");
 ImplementedInterfaceNames(my_calculator);
 Scanner scanner = new Scanner(System.in);
 int n = scanner.nextInt();
 System.out.print(my_calculator.divisor_sum(n) + "\n");
 scanner.close();
 }

 private static void ImplementedInterfaceNames(Object o){
 Class[] theInterfaces = o.getClass().getInterfaces();
 for (int i = 0; i < theInterfaces.length; i++){
 String interfaceName = theInterfaces[i].getName();
 System.out.println(interfaceName);
 }
 }
}

interface AdvancedArithmetic {
 int divisor_sum(int number);
}

class MyCalculator implements AdvancedArithmetic {
 @Override
 public int divisor_sum(int number) {
 int result = 1 + (number > 1 ? number : 0);
 for (int index = 2 ; index < number ; index++) {
 result += number % index == 0 ? index : 0 ;
 }
 return result;
 }
}