Exceptions

[Jeffery Miller]

I have another questoin about a piece of code...I need to make this program loop to read integer values until the user enters 999 and NOT blow-up if they enter something dumb like "abc", "$1,000", or "13.25". Examples would help

  import java.io.*;
public class Lab31B {
  public static void main(String[] args) {
    int x = 0;
    while (x != 999) {
      System.out.print("Enter an integer value or 999 to exit: ");
      x = readInt();
      if (x != 999)
        System.out.println("You entered: " + x);
      else
        System.out.println("Goodbye...");
    }
  }
  public static int readInt() throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    return Integer.parseInt(br.readLine());
  }
} 
 
  

[fred rosenberger]

We're not really here to write code for you. Try something. Show us you have made some effort. You'll get suggestions, tips, and guidance. but nobody should just post the solution for you.

So, where do you think the problem is? What can you try changing to fix it?
[ January 16, 2008: Message edited by: Fred Rosenberger ]

[M Newhouse]

I am just starting in Java, and I have a similar problem. Mine reads a string which I convert into a double. But, if a non-numeric character is entered instead, I get an error when parsing into a double. Any help? Thanks!

[Jim Yingst]

Well, sounds like you're both doing about the same thing. I would recommend you try to catch the exception. Have you seen examples of a try/catch block? That's what you would use here. Jeffry needs to loop until a valid number is entered, so there will be a loop of some sort too. (I can't tell for M Newhouse - what do you want to do instead of an error?) The loop must be positioned so that you stay inside the loop when an exception is thrown. Unfortunately you're also inside the loop when an exception isn't thrown, so the challenge may be to figure out how to get out of the loop when the number is valid. Let's see what you can come up with.

[Petrus Pelser]

Have a look at NumberFormatException.

[M Newhouse]

Thanks for the starting point. I'll take a look and see what I can find.

[M Newhouse]

The NumberFormatException (with the try/catch) worked great. Thanks for your help.
[ January 17, 2008: Message edited by: M Newhouse ]