do-while问题！ ！ [英] Problem with do-while ! !

问题描述

我有问题，如何执行此代码?

-------------------------------------------------- -
###欢迎使用Uber票价计算器###
-------------------------------------------------- -
| 1:获取有关可用游乐设施的票价信息|
| 2:为您的旅途获取车费估算|
| 3:提交您的骑行评级|
| 4:退出并显示摘要|
-------------------------------------------------- -
>请输入您的选择...(1-4):5

选择无效！请重试



-------------------------------------------------- -
###欢迎使用Uber票价计算器###
-------------------------------------------------- -
| 1:获取有关可用游乐设施的票价信息|
| 2:为您的旅途获取车费估算|
| 3:提交您的骑行评级|
| 4:退出并显示摘要|
-------------------------------------------------- -
>请输入您的选择...(1-4):1

-------------------------------------
***骑*** ***
-------------------------------------
| X或x:UberX |
|升或升:UberXL |
| B或b:UberBlack |
| R或r:返回主菜单|
-------------------------------------

我尝试过的事情:

I have problem ,How can do this code?

----------------------------------------------------
### Welcome to Uber Fare Calculator ###
----------------------------------------------------
| 1 : Get fare information about available rides |
| 2 : Get a Fare Estimate for your Journey |
| 3 : Submit Rating of your Ride |
| 4 : Exit and display summary |
----------------------------------------------------
> Please enter your choice... (1-4):5

Invalid Choice!! Please Try again



----------------------------------------------------
### Welcome to Uber Fare Calculator ###
----------------------------------------------------
| 1 : Get fare information about available rides |
| 2 : Get a Fare Estimate for your Journey |
| 3 : Submit Rating of your Ride |
| 4 : Exit and display summary |
----------------------------------------------------
> Please enter your choice... (1-4):1

-------------------------------------
*** RIDES ***
-------------------------------------
| X or x : UberX |
| L or l : UberXL |
| B or b : UberBlack |
| R or r : Return to Main Menu |
-------------------------------------

What I have tried:

Scanner t = new Scanner(System.in);
      int cho;
       do {
          System.out.println("----------------------------------------------------");
          System.out.printf("%-11s%10s%11s", "###", "Welcome to Uber Fare Calculator", "###\n");
          System.out.println("----------------------------------------------------");
          System.out.println("| 1 : Get fare information about available rides   |");
          System.out.println("| 2 : Get a Fare Estimate for your Journey         |");
          System.out.println("| 3 : Submit Rating of your Ride                   |");
          System.out.println("| 4 : Exit and display summary                     |");
          System.out.println("----------------------------------------------------");
          System.out.print(" > Please enter your choice... (1-4):");
          cho = t.nextInt();
          }while(cho<1 || cho>4);

我想当用户输入1,2,3或4时转到另一个循环，但是当用户输入另一个时，我想要此消息

I want when the user enter 1,2,3 or 4 go to another loops but when the user enter another choose i want this massage

System.out.println("\n\t\tInvalid Choice!! Please Try again");

推荐答案

do ... while在条件为真时继续循环:

do ... while continues to loop while teh condition is true:

i = 0;
do {
   System.out.println(i);
   i = i + 1;
   } while (i < 5);

将打印:

0
1
2
3
4

仅当cho小于1或大于4时，您的条件才成立:对于集{1、2、3、4}中的所有cho值，它都是错误的.
因此，当用户输入有效的菜单选项时，它将立即退出循环.
更改条件，添加代码以处理菜单选项，它应该开始起作用.

Your condition is only true when cho is either less than 1 or greater than 4: it is false for all values of cho in the set {1, 2, 3, 4}
So when a user enters a valid menu choice, it immediately exits the loop.
Change your condition, add the code to handle your menu choices, and it should start to work.

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