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Thread: exception question

  1. #1
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    Default exception question

    Is the call to getNum(in) in retry(in) a recursive call??

    What I'm trying to do is keep requesting input when NumberFormatException
    is thrown.

    import java.io.InputStreamReader;
    import java.io.BufferedReader;
    import java.io.IOException;
     
    public class test
    {
       private static int retry(BufferedReader in) throws IOException
       {
          System.out.print("Enter number: ");
          return test.getNum(in);
       }
     
       public static int getNum(BufferedReader in) throws IOException
       {
          int num;
           try
           {
              num = Integer.parseInt(in.readLine());
           }
           catch(NumberFormatException e)
           {
              System.out.println("INVALID INPUT!!!\n");
              num = retry(in);  
           }
          return num;
       }
     
     
       public static void main(String[] args) 
         {
            BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
            String name;
            int num1, num2;
     
          try
            {
              System.out.print("Enter a line: ");
              name = input.readLine();
              System.out.println("Hello : " + name);
     
              System.out.print("Enter first number: ");
              num1 = test.getNum(input);
     
              System.out.print("Enter second number: ");
              num2 = test.getNum(input);
     
              System.out.println(name + " the answer is " + (num1 + num2));
            }
          catch(IOException e)
            {
              System.out.println("IO ERROR!!!!\n" + e.getMessage() + "\n");
            }
     
         }
     
    }


  2. #2
    Forum old-timer
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    Default Re: exception question

    Yes, it is a recursive call. Seems to work OK - what's the problem?

    If you find recursion awkward to follow, you could loop instead, and it would be nice to make the prompts clearer to the user by repeating the prompt and input until valid input is received, e.g.
    prompt = "Enter first number"
    input = getInput(prompt)
    while not valid input
      input = getInput(prompt)
    end while

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