求素数

public class Prime {
int i = 100;
int num ;
public static boolean isPrime(int num) {
   for(int j=2; j<=Math.sqrt(num); j++) {
    if(num%j == 0) {
     return false;
    }
   }
   return true;
}
public static void main(String[] args) {
   for(int k=2; k<=100; k++) {
    if(isPrime(k)) {
     System.out.print(k+" ");
    }
   }
}
}