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javaexceptionformatexception

Exception Handling works only once in running program


Initially I tried to put the try statement into the while loop, however, I was encountered with several errors. The program runs perfectly except when I input a irregular character once it gives me the Printed line I inputted I created, however, when I inputted another one again, the line does not pop up and rather gives me a format exception error.

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
  }
}

Solution

  • You want something to catch the exception around the Double.parseDouble

    for example.

     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
      }