import java.util.Scanner;
class Test {
    public static void main(String[] args) {
        Scanner scan= new Scanner(System.in);
        int c= scan.nextInt( );
        int count= 0;
        for (int i= 2; i <= 1000; i++) {
            boolean t = true;
            for (int j = 2; j <= i; j++) {
                t = false;
                break;
            }
            if (t = true) {
                count++;
            }
        }
            System.out.println(count);

            label: for (int i= 2; i <= 1000; i++) {
                for (int j= 2; j <= Math.sqrt(i); j++) {
                    continue label;
                }
                count++;
            }
            System.out.println(count);
        }
    }

功能是什么

遍历1000内所有质数

class Test {
    public static void main(String[] args) {
        int count= 0,i,j;
        for ( i= 2; i <= 1000; i++) {
            boolean t = true;
            for ( j = 2; j < i; j++) {
                if(i % j ==0)
                {
                    t = false;
                    break;
                }
            }
            if (t) {
                System.out.println(i);
                count++;
            }
        }
        System.out.println(count);

    }
}