PrimeChecker.java

// https://www.hackerrank.com/challenges/prime-checker/problem

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Set;
import static java.lang.System.in;

public class PrimeChecker {
    public static void main(String[] args) {
        try{
            BufferedReader br=new BufferedReader(new InputStreamReader(in));
            int n1=Integer.parseInt(br.readLine());
            int n2=Integer.parseInt(br.readLine());
            int n3=Integer.parseInt(br.readLine());
            int n4=Integer.parseInt(br.readLine());
            int n5=Integer.parseInt(br.readLine());
            Prime ob=new Prime();
            ob.checkPrime(n1);
            ob.checkPrime(n1,n2);
            ob.checkPrime(n1,n2,n3);
            ob.checkPrime(n1,n2,n3,n4,n5);
            Method[] methods=Prime.class.getDeclaredMethods();
            Set<String> set=new HashSet<>();
            boolean overload=false;

            for(int i=0;i<methods.length;i++) {
                if(set.contains(methods[i].getName()))
                {
                    overload=true;
                    break;
                }
                set.add(methods[i].getName());
            }
            if(overload) {
                throw new Exception("Overloading not allowed");
            }
        } catch(Exception e) {
            System.out.println(e);
        }
    }

    private static class Prime {
        private final Set<Integer> primeNumbers = new HashSet<>();

        public void checkPrime(int... numbers) {
            for (int number : numbers) {
                if (isPrime(number)) {
                    System.out.print(number + " ");
                }
            }
            System.out.println();
        }

        private boolean isPrime(int number) {
            if (primeNumbers.contains(number)) {
                return true;
            }

            if (number == 1) {
                return false;
            }

            for (int index = 2 ; index * index <= number ; index++) {
                if (number % index == 0) {
                    return false;
                }
            }

            primeNumbers.add(number);
            return true;
        }
    }
}