public class Prime {
 public static void main(String[] args) {
   int counter = 0;
   for (int i = 1; i <= 100; i++) {
     if (isPrimeNumber(i)) {
       counter++;
              System.out.println(counter + " : " + i);
     }
   }
 }​ ​public static boolean isPrimeNumber(int i) {
       int factors = 0;
       int j = 1;
​
       while(j <= i)
       {
           if(i % j == 0)
           {
               factors++;
           }
           j++;
       }
       return (factors == 2);
 }
}