判斷一個數是否是素數

 

package com.test1;

import java.util.Scanner;
import java.math.*;

public class test8 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Test t = new Test();
        t.play();

    }

}

class Test {
    public void play() {
        System.out.println("請輸入數字");
        Scanner s = new Scanner(System.in);
        int m = s.nextInt();

        int k = (int) Math.sqrt(m);
        int i = 2;
        // System.out.println(number);
        for (i = 2; i <= k; i++) {
            if (m % i == 0) {
                break;
            }
    }

        if (i > k) {
            System.out.println("是素數");
        } else

        {
            System.out.println("不是素數");
        }

    }
}