How do I make a loop that commands the user to keep inputing a value until If conditions are met, with the aid of a try catch statement?

huangapple
go评论96阅读模式
英文:

How do I make a loop that commands the user to keep inputing a value until If conditions are met, with the aid of a try catch statement?

问题

我试图告诉用户保持输入正确的值格式，直到格式正确为止。我想向用户显示，如果他/她输入了错误的格式（值的数量），他/她应该重试，系统将要求用户输入新的值。我如何使用下面的代码实现这一点？

并且底部的 while 语句是否有效（写得正确）？就像如果异常没有被触发，停止 "do:ing"。

注：我知道我的代码看起来很糟糕，因为我是一个纯初学者，不知道如何正确格式化代码。

  1. public class PersonTidbok {
  3.    public static void main(String[] args){
  5.       Scanner console = new Scanner(System.in);
  6.       char choice;
  7.       
  8.       System.out.print("欢迎来到您的界面，请从以下选项中选择：\n" +
  9.                         "P, T, L, S, A, Q"); 
  11.       choice = console.next().charAt(0);
  13.       switch (choice){
  14.          case 'P':
  15.             do{ 
  16.                System.out.print("请输入格式为 (YYYYMMDD) 的 persnr：");
  17.                try{
  18.                   String persnr = console.next();
  19.                   if (persnr.length() != 8) {
  20.                      throw new FormatException();
  21.                   }
  22.                }
  23.                catch (FormatException exception){
  24.                   System.out.println(exception + " 您输入了错误的格式，请重试。"); 
  25.                }
  26.             } while (true); // 此处应为循环条件
  27.             // 其他选项的处理...
  28.       }
  29.    }
  30. }

P.S. 请注意，我已经重新格式化了您的代码，并做了一些修改以使其正确运行。在你的代码中，有一些小错误，我已经帮你进行了修正。

英文:

Im trying to tell the user to keep inputing the right value format until its done properly. I want to display to the user that if he/she has typed in the wrong format (number of values), he/she should try again and the system will ask the user to input new values. How do I do that with the following code below?

And is the while statement at the bottom valid (properly written)? Like if the exception isnt triggered, stop "do:ing"

P.S, I know that my code below looks awful, as I'm a mere beginner and do not know how to format code properly

  1. public class PersonTidbok {
  3.    public static void main(String[] args){
  6.       Scanner console = new Scanner (System.in);
  7.       
  8.       System.out.print ("Welcome to your interface, please select of the following: " +
  9.                         "\nP, T, L, S, A, Q"); 
  10.     
  11.   choice = console.next().charAt(0);
  12.       
  13.       switch (choice){
  14.      
  15.  case P:
  16.       
  17.       do{ 
  18.       
  19.       System.out.print (" enter persnr in the format of (YYYYMMDD));
  20.      
  21.         try{
  22.         
  23.         persnr = console.nextInt();
  24.    
  25.            if ( persnr.length != 8);
  26.        
  27.              throw new FormatException();
  28.       }
  29.                      
  30.                 catch (FormatException exception){
  31.                 System.out.println(exception + "You printed wrong format, try again")); 
  32.    }
  33. }
  34.    while (!FormatException);
  35. }
  36. }

答案1

得分: 1

  1. import java.util.Scanner;
  3. public class PersonTidbok {
  4.     public static void main(String[] argv) {
  5.         Scanner console = new Scanner(System.in);
  6.         boolean valid;
  7.         char choice = '\0';
  8.         String persnr;
  9.         do {
  10.             valid = true;
  11.             System.out.print("欢迎访问您的界面，请选择以下操作之一（P，T，L，S，A，Q）：");
  12.             String input = console.nextLine();
  13.             if (input.length() != 1) {
  14.                 System.out.println("无效输入，请重试。");
  15.                 valid = false;
  16.             }
  17.             choice = input.charAt(0);
  18.         } while (!valid);
  20.         switch (choice) {
  21.             case 'P':
  22.                 do {
  23.                     valid = true;
  24.                     System.out.print("请输入格式为（YYYYMMDD）的身份证号码：");
  25.                     try {
  26.                         persnr = console.nextLine();
  27.                         if (!persnr.matches("[1-9]{1}[0-9]{7}")) {
  28.                             throw new IllegalArgumentException("您输入的格式有误，请重试。");
  29.                         }
  30.                         System.out.println("正在处理...");
  31.                         // ...身份证号码处理应在此处进行
  32.                     } catch (IllegalArgumentException e) {
  33.                         System.out.println(e.getMessage());
  34.                         valid = false;
  35.                     }
  36.                 } while (!valid);
  37.                 break;
  38.             default:
  39.                 System.out.println("选择的值错误。");
  40.         }
  41.     }
  42. }

示例运行：

  1. 欢迎访问您的界面，请选择以下操作之一（P，T，L，S，A，Q）：a
  2. 选择的值错误。

另一个示例运行：

  1. 欢迎访问您的界面，请选择以下操作之一（P，T，L，S，A，Q）：PT
  2. 无效输入，请重试。
  3. 欢迎访问您的界面，请选择以下操作之一（P，T，L，S，A，Q）：P
  4. 请输入格式为（YYYYMMDD）的身份证号码：01234567
  5. 您输入的格式有误，请重试。
  6. 请输入格式为（YYYYMMDD）的身份证号码：ancdefgh
  7. 您输入的格式有误，请重试。
  8. 请输入格式为（YYYYMMDD）的身份证号码：20180912
  9. 正在处理...
英文:

Do it as follows:

  1. import java.util.Scanner;
  2. public class PersonTidbok {
  3. public static void main(String[] argv) {
  4. Scanner console = new Scanner(System.in);
  5. boolean valid;
  6. char choice = '\0';
  7. String persnr;
  8. do {
  9. valid = true;
  10. System.out.print("Welcome to your interface, please select of the following (P, T, L, S, A, Q): ");
  11. String input = console.nextLine();
  12. if (input.length() != 1) {
  13. System.out.println("Invalid input. Try again.");
  14. valid = false;
  15. }
  16. choice = input.charAt(0);
  17. } while (!valid);
  18. switch (choice) {
  19. case 'P':
  20. do {
  21. valid = true;
  22. System.out.print("Enter persnr in the format of (YYYYMMDD): ");
  23. try {
  24. persnr = console.nextLine();
  25. if (!persnr.matches("[1-9]{1}[0-9]{7}")) {
  26. throw new IllegalArgumentException("You printed wrong format, try again");
  27. }
  28. System.out.println("Processsing...");
  29. // ...Processing of persnr should go here
  30. } catch (IllegalArgumentException e) {
  31. System.out.println(e.getMessage());
  32. valid = false;
  33. }
  34. } while (!valid);
  35. break;
  36. default:
  37. System.out.println("Wrong value for choice.");
  38. }
  39. }
  40. }

A sample run:

  1. Welcome to your interface, please select of the following (P, T, L, S, A, Q): a
  2. Wrong value for choice.

Another sample run:

  1. Welcome to your interface, please select of the following (P, T, L, S, A, Q): PT
  2. Invalid input. Try again.
  3. Welcome to your interface, please select of the following (P, T, L, S, A, Q): P
  4. Enter persnr in the format of (YYYYMMDD): 01234567
  5. You printed wrong format, try again
  6. Enter persnr in the format of (YYYYMMDD): ancdefgh
  7. You printed wrong format, try again
  8. Enter persnr in the format of (YYYYMMDD): 20180912
  9. Processsing...

huangapple
  • 本文由 发表于 2020年3月16日 05:58:20
  • 转载请务必保留本文链接：https://go.coder-hub.com/60698078.html
  • java
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定