1. public void test() {
    2.     boolean[] signs = new boolean[100];
    3.     for (int i = 2; i * i < 100; i++) {
    4.       if (!signs[i]) {
    5.         for (int j = i * i; j < 100; j += i) {
    6.           signs[j] = true;
    7.         }
    8.       }
    9.     }
    10.     for (int i = 2; i < 100; i++) {
    11.       if (!signs[i]) {
    12.         System.out.println(i);
    13.       }
    14.     }
    15. }