實訓JAVA語言設計——產生一個2-K之間的隨機整數，判斷一個數是否是素數

 

1                     import java.io.*; 

2                        import java.util.*;

3                          public class J2_13 { 

4                            public static void main(String a[]) {

5                              Scanner scanner = new Scanner(System.in); /*構造一個Scanner對象，其傳入參數為System.in*/

6                          System.out.println("Please enter a number to limit the random number that yout want:");

7                          int k= scanner.nextInt(); /*讀取一個int數值k */ 

8                         int p= (int)(2+(k-2)*Math.random()) ;/*產生一個2-K之間的隨機整數*/

9                        if(yes(p)) 

10                     System.out.println(p+" is prime。");  

11                   else 

12                   System.out.println(p+" is not prime。"); 

13                    return; 

14                   } 

15                   /*判斷一個數是否是素數*/

16                   public static boolean yes(int q) { 

17                        boolean t=true; 

18                           for(int i=2;i<q;i++) 

19                               if(q%i==0) { 

20                          t=false; 

21                    break; 

22                    } 

23                   return t; /*返回boolean值*/

24                   } 

25       }