Hello. I am having a problem generating the prime numbers from user input. The problem lies in the factorize method. I think I am really close to getting this to work, but I cannot seem to figure out the last detail that I need to include. Can anyone help? Thank you.

```
import java.util.*;
public class PrimeFactors {
public PrimeFactors() {
int number = 0;
while(number != -1) {
number = readIntFromUser();
if(isPrime(number)) {
System.out.println(number+" is a prime!");
}
else {
System.out.println(number+"'s prime factors are: "+factorize(number));
}
}
System.out.println("Bye!");
}
public Set<Integer> factorize(int number) {
Set<Integer> primeFactors = new TreeSet<Integer>();
int div = 2;
while (number > 1) //WHILE number is more than one
{
if ( div % number ==0)
{
primeFactors.add(new Integer(div));
number = number / div;
}
else
div++; //increase 'div' by one
}
return primeFactors;
}
public boolean isPrime(int number) {
int root = (int)Math.sqrt(number);
for(int i = 2; i <= root; i++) {
if(number%i == 0) {
return false;
}
}
return true;
}
public int readIntFromUser() {
Scanner scanner = new Scanner(System.in);
System.out.print("Please enter a number, -1 to terminate:" );
return scanner.nextInt();
}
public static void main(String[] args) {
new PrimeFactors();
}
}
```