50道编程题之02: 判断a,b之间有多少个素数，并输出所有素数

import java.util.ArrayList;
import java.util.Scanner;

/**
 * Created by 莫文龙 on 2018/3/23.
 */

public class Main{
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int start = scanner.nextInt();
        int end = scanner.nextInt();
        int count = 0;
        if (start <= 0 || end < start) {
            throw new RuntimeException("输入的数据有误");
        }

        ArrayList<Integer> list = new ArrayList<>();
        for (int i = start ; i <= end ; i ++) {
            if (i == 1) continue;
            if (i == 2) {
                count ++;
                list.add(2);
                continue;
            }
            boolean flag = true;
            for (int j = 2 ; j < i ; j ++) {
                if (i % j == 0) {
                    //证明不是素数
                    flag = false;
                    break;
                }
            }
            if (flag) {
                count ++;
                list.add(i);
            }
        }
        System.out.println(start + "-" + end + "的素数个数为:" + count);
        for (Integer i : list) {
            System.out.print(i + ",");
        }
    }

}