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Thread: exception question

  1. #1
    Junior Member
    Join Date
    Jul 2011
    Thanked 0 Times in 0 Posts

    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;
              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;
              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
    Join Date
    Nov 2008
    Faversham, Kent, UK
    My Mood
    Thanked 58 Times in 54 Posts

    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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