Java InputMismatchException错误

Question

我已经完成了从ft和cm进行一些转换的任务。我已经完成了大部分工作并且转换确实有效。我还想在输入字符串时添加A negative number...或A non-digit...的语句，例如，或者为负数，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testProgram.NegativeNumberException时，我会得到-9的输出。例如，当我输入testProgram.NonDigitNumberException时，joe。{/ p>

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

除了@ Scary的建议，您可以在自定义异常中添加构造函数 -

http://localhost:3000/pixel_data

这将帮助您在

时打印信息

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