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最初我试图将try语句放入while循环中，但是遇到了几个错误。该程序运行完美，除非我输入一个不规则字符，一旦它给了我我输入的我创建的打印行，但是，当我再次输入另一个时，该行没有弹出，而是给我一个格式异常错误。

AddNumbersrealone2.java

import java.io.*;

// create the class
public class AddNumbersrealone2
{
    // allows i/o
  public static void main (String [] args) throws IOException
  {   // initalize variables and strings
    BufferedReader myInput = new BufferedReader  (new InputStreamReader (System.in));
    String sumNumbers;
    //String go;
    double num ;
    double total = 0.0;

    // asks user questions and instructions
    System.out.println("Hello, the following program will ask for your input of a number ");
    System.out.println("Each time you input a number a running total will be added to each previous number")  ;
    System.out.println("Once ready input a number to start!");
    // try and catch block      
    try {

      num = 0;

      // while statement if this occurs stop the program, in this case if a negative integer is inputted

      while (num >= 0) {

        // Contious question asked  
        System.out.println("Input another number..."); 
        sumNumbers = myInput.readLine();
        num = Double.parseDouble (sumNumbers);

        // calculates number (Running total)
        total = total + num;
        System.out.println(total);

        // end error trap
      }
    }
    catch  (Exception e){
      System.out.println("Please refrain from entering regular characters!");
      num = 0;

      // re- while statement if this occurs stop the program, in this case if a negative integer is inputted

      while ( num >= 0) {

        // input question after a character is inputted
        System.out.println("Please input a number: ");
        sumNumbers = myInput.readLine();
        num = Double.parseDouble (sumNumbers);

        total = total + num;
        System.out.println(total);

        // ending statement
      }
    }
    System.out.println("You entered a negative number, the program will exit now");
    System.out.println("Good-bye!");

    // Complete class body
  }
}
4

2 回答 2

2

你想要一些东西来捕捉 Double.parseDouble 周围的异常

例如。

 while(num >= 0)
    {
    // input question after a character is inputted
       System.out.println("Please input a number: ");
       sumNumbers = myInput.readLine();
       try{
            num = Double.parseDouble (sumNumbers);
            total = total + num;
            System.out.println(total);
       } catch(Exception e)
       {
            System.out.println("Please enter a proper number");
       }    


            // ending statement
  }
于 2013-02-26T21:33:46.917 回答
0

您的问题是，一旦引发第一个异常，您的程序就会被 catch 语句内的 while() 循环所捕获。因此，如果输入了另一个无效输入，则会在没有 try-catch 语句的第二个 while 循环中处理它。一个好的解决方法是让您的 try 语句仅包含您说 num = Double.parseDouble (sumNumbers); 的行。当你捕捉到异常时，以 continue 结束它；语句，以便您的程序循环回到开头并要求另一个输入。

于 2013-02-26T21:32:46.457 回答