Java案例-判断随机整数是否是素数

package teacher01;
public class PrimeTest {
 public static void main(String[] args) {
 for (int i = 0; i < 100; i++) {
 int num = (int) (Math.random() * 1000);
 PrimeTest t = new PrimeTest();
 if (t.isPrime(num)) {
 System.out.println(num + "是素数！");
 } else {
 System.out.println(num + "不是素数！");
 }
 System.out.println();
 }
 }
 public boolean isPrime(int num) {
 for (int i = 2; i <= num / 2; i++) {
 if (num % i == 0) {
 System.out.println(num + "第一个被" + i + "整除！");
 return false;
 }
 }
 return true;
 }
}