猴子吃桃

 1 import java.util.Scanner;
 2 public class Test{
 3     public static void main(String[] args) {
 4         Scanner scan = new Scanner(System.in);
 5         System.out.println("请输入当前天数：\n");
 6         int day = 0,peachNum = 0;
 7         for (;;){
 8         //当用户输入有问题时，可以用循环来实现让用户重新输入
 9         day = scan.nextInt();
10         if (day < 1)
11             System.out.print("天数必须大于等于1！请重新输入\n");
12         else break;
13         }
14         for (;;){
15         //当用户输入有问题时，可以用循环来实现让用户重新输入
16         System.out.println("请输入当前桃子数：\n");
17         peachNum = scan.nextInt();
18         if (peachNum < 0)
19             System.out.print("桃子数必须大于等于0！请重新输入\n");
20         else break;
21         }
22         monkey pNum = new monkey();
23         pNum.peach(day,peachNum);
24     }
25 }
26 
27 class monkey{
28     public void peach(int day,int peachNum){
29         if (day > 1)
30             peach(day - 1,2 * (1 + peachNum));
31         if (day == 1)
32             System.out.print("原先一共有" + peachNum + "个桃子");
33     }
34 }