给定一个数字，判定一个数字是否是素数

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int num = scanner.nextInt();
for (int j = 0; j <= num; j++) {
int i = 2;
for (; i <= Math.sqrt(j); i++) {
if (num % i == 0) {
System.out.println("不是素数");
break;
}
}
if (i > Math.sqrt(num)) {
System.out.println("是素数");
break;
}
}
}