在线程 "main" java.util.InputMismatchException 中获取异常

Question

我正在尝试一个一个地输入，然后尝试对它们执行操作。按照我的代码。

   import java.util.Scanner;

    public class PlayerRoster {
       public static void main(String[] args) {
          Scanner scnr = new Scanner(System.in);
      
          final int LENGTH = 5;
          final char quit = 'q';
          char uin = 'z';
          int jersey = 0;
          int chng = 0;
      
          int[] number = new int[LENGTH];
          int[] rating = new int[LENGTH];
      
          for(int i = 0; i < LENGTH; i++){
             System.out.println("Enter player "+(i+1)+"'s jersey number:");
             number[i] = scnr.nextInt();
             System.out.println("Enter player "+(i+1)+"'s rating:\n");
             rating[i] = scnr.nextInt();
          }
          for(int i = 0; i < LENGTH; i++){
             if (i == 0)
                System.out.println("ROSTER");
      
                 System.out.println("Player " + (i + 1) + " -- Jersey number: " + (number[i]) + ", Rating: " + (rating[i]));
             if (i == 4)
                System.out.println("");
      
          }
          while (uin != quit){
         
             System.out.println("MENU");
             System.out.println("u - Update player rating");
             System.out.println("a - Output players above a rating");
             System.out.println("r - Replace player");
             System.out.println("o - Output roster");
             System.out.println("q - Quit\n");
       
             System.out.println("Choose an option:");
              uin = scnr.next().charAt(0);
      
             if (uin == 'o')
                for(int i = 0; i < LENGTH; i++){
                   if (i == 0)
                      System.out.println("ROSTER");
                      System.out.println("Player " + (i + 1) + " -- Jersey number: " + (number[i]) + ", Rating: " + (rating[i]));
                   if (i == 4)
                      System.out.println("");
                }
         
         
             if (uin == 'u')
                System.out.println("Enter a jersey number: ");
                   chng = scnr.nextInt();
         
          }  
       }
    }

我目前不专注于逻辑，因为我无法接受输入，因为我正在 Exception in thread "main" java.util.InputMismatchException 当我只是想获得更多用户输入时。

我的输入是： 20 5 30 2 50 4 60 8 93 9 u 20 q

我已经尝试了从 char 到正常 Strings 的所有方法。感觉就像扫描仪不工作一样。

    Exception in thread "main" java.util.NoSuchElementException
        at java.base/java.util.Scanner.throwFor(Scanner.java:937)
        at java.base/java.util.Scanner.next(Scanner.java:1594)
        at java.base/java.util.Scanner.nextInt(Scanner.java:2258)
        at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
        at PlayerRoster.main(PlayerRoster.java:55)

Answer 1

问题是代码块

 if (uin == 'u')
        System.out.println("Enter a jersey number: ");
           chng = scnr.nextInt();

因为你只需要球衣号码，以防用户输入 'u' your chng = scnr.nextInt();应该在 if 块内。在您的情况下，即使用户将输入作为 'q'，它仍然期望用户提供更多输入，并且您可能只是给出空白 space 在这种情况下给您 InputMisMatchException.

要修复它，请将代码更新为

if (uin == 'u')
{
     System.out.println("Enter a jersey number: ");
     chng = scnr.nextInt();
}

所以现在，如果您将输入作为 'q'，您的循环将停止执行，这是预期的输出。

在线程 "main" java.util.InputMismatchException 中获取异常

Getting exception in thread "main" java.util.InputMismatchException

java

inputmismatchexception