我需要一個Java掃描器'重置'無效字符修復

Question

我是一個新的人類學習代碼！

我的掃描儀出了問題，我需要它對無效字符進行「重置」。

我的代碼：

public class Lemonade { 

static int m = 150; 
private static Scanner scan; 

public static void main(String[] args) { 

    int day = 1; 

    for(int gameover = m; gameover > 0; day++) { 
    int Random = (int) (Math.random() * 100); 
    if(Random <= 25) { 
     System.out.println("Great Chance!"); 
     System.out.println("--------------------------------"); 
    } 
    else if(Random <= 50) { 
     System.out.println("Good Chance!"); 
     System.out.println("--------------------------------"); 
    } 
    else if(Random <= 75) { 
     System.out.println("Bad Chance!"); 
     System.out.println("--------------------------------"); 
    } 
    else if(Random <= 100) { 
     System.out.println("Awful Chance!"); 
     System.out.println("--------------------------------"); 
    } 

    int count = 0; 

    int none = 0; 

    scan = new Scanner(System.in); 

    System.out.println("Enter a number between 0 and " + m + "!"); 

    count = scan.nextInt(); 

    if(count >= none && count <= m) { 
     System.out.println("You entered " + count + "!"); 
     System.out.println("--------------------------------"); 
     day = day + 1; 
     m = m - count; 
     System.out.println("Day " + day); 
    } 
    else { 
     System.out.println("Enter a number between 0 and " + m + "."); 
     count = scan.nextInt(); 
    } 

    } 
} 
} 

現在是我的問題如何得到這個「重置」的無效字符像「F」，如掃描儀只接受數字。

感謝您的幫助！

Answer 1

如果我理解你正確，那麼這是你正在尋找的， 如果用戶輸入invaild字符而不是int，則會拋出InputMismatchException。你可以使用循環直到用戶輸入一個整數

import java.util.Scanner; 
import java.util.InputMismatchException; 


class Example 
{ 
    public static void main(String args[]) 
    { 
     boolean isProcessed = false; 
     Scanner input = new Scanner(System.in); 
     int value = 0; 
     while(!isProcessed) 
     { 

      try 
      { 
       value = input.nextInt(); 
     //example we will now check for the range 0 - 150 
     if(value < 0 || value > 150) { 
      System.out.println("The value entered is either greater than 150 or may be lesser than 0"); 
     } 
     else isProcessed = true; // If everything is ok, Then stop the loop 
      } 
      catch(InputMismatchException e) 
      { 
       System.out.print(e); 
     input.next(); 
      } 

     } 

    } 
} 

如果這不是你想要的，請讓我知道！