Java InputMismatchException 错误

Question

我接到了一项任务，要将英尺和英寸转换为厘米。我已经了解了其中的大部分内容，并且转换确实有效。我还想在输入字符串时包含 A negative number... 或 A non-digit... 的语句，例如，或负数，以显示所述消息。

我遇到的问题是，当我输入字符串或负数时，例如，当我输入 -9 时，我得到 testProgram.NegativeNumberException 的输出。而testProgram.NonDigitNumberException，当我输入joe，例如

我认为 catch 有问题，但不确定它不会点击的确切位置。

package testProgram;
import java.util.InputMismatchException;
import java.util.Scanner;

public class conversion{

   public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       double cm = -1;
       while(cm == -1){
       cm = convertToCentimeters(scan);

       if(cm!=-1){
       System.out.println("Your result = " +cm);
       }
       else{
           System.out.println("Please enter the values again.");
       }
       scan.nextLine();
       }
   }
   public static double convertToCentimeters(Scanner scan){
       double centimeters = -1;
       try{
           double foot = getFootValue(scan);
           double inch = getInchValue(scan);
           double totalInches = foot * 12 + inch;
           centimeters = totalInches * 2.54;

           }catch(NegativeNumberException e1){
               System.out.println(e1);
           }
           catch(NonDigitNumberException e2){
               System.out.println(e2);
           }
           return centimeters;
   }
   public static double getFootValue(Scanner scan) throws NegativeNumberException, NonDigitNumberException{
       try{
       System.out.println("Enter the foot value: ");
       double foot = scan.nextDouble();
       if(foot <= 0){
           throw new NegativeNumberException ("A negative foot value has been entered.");
       }
       return foot;
       }
       catch(InputMismatchException e){
           throw new NonDigitNumberException ("A non-digit foot value has been entered.");
       }
   }
   public static double getInchValue(Scanner scan)throws NegativeNumberException, NonDigitNumberException{
   try{
       System.out.println("Enter the inch value: ");
       double inch = scan.nextDouble();
       if(inch <= 0){
           throw new NegativeNumberException ("A negative inch value has been entered.");
       }
       return inch;
       }
       catch(InputMismatchException e){
           throw new NonDigitNumberException ("A non-digit inch value has been entered.");
       }
   }
}

Answer 1

替代@Scary 的建议，您可以将构造函数添加到您的自定义异常中，如 -

NegativeNumberException(String str) {
    System.out.println(str);
}

这将帮助您在

时打印消息

throw new NegativeNumberException ("A n....");

Java InputMismatchException 错误

Java InputMismatchException Error

java

inputmismatchexception