Sum Prime Non Prime

import java.util.Scanner;

public class SumPrimeNonPrime {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String input = scan.nextLine();
        int primeSum = 0;
        int nonPrimeSum = 0;

        while (!"stop".equals(input)) {
            int currentNumber = Integer.parseInt(input);
            if (currentNumber < 0) {
                System.out.println("Number is negative.");
                input =scan.nextLine();
                continue;
            }
            boolean isPrime = true;
            for (int i = 2; i < currentNumber; i++) {
                if (currentNumber % i == 0) {
                    isPrime = false;
                    break;
                }
            }
            if(isPrime) {
                primeSum +=currentNumber;
            } else {
                nonPrimeSum +=currentNumber;
            }
            input = scan.nextLine();
        }

        System.out.printf("Sum of all prime numbers is: %d%nSum of all non prime numbers is: %d", primeSum, nonPrimeSum);
    }
}