Thread: Input Validation

Hi there, can anyone help me to validate the input value? example when i pressed character on the keyboard it will ask us to press number only.. anyone got any idea how to validate it?
thanks in advance...

import javax.swing.*;
 
public class additiontutor
{
 public static void main(String args[])
 {
  int number1 = (int)(System.currentTimeMillis() % 10);
  int number2 = (int)(System.currentTimeMillis() * 7 % 10);
 
  String answerString = JOptionPane.showInputDialog
    ("What is " + number1 + " + " + number2 + "?");
 
  int answer = Integer.parseInt(answerString);
 
  JOptionPane.showMessageDialog(null,
    number1 + " + " + number2 + " = " + answer + " is " +
    (number1 + number2 == answer));
 
 }
}

Several ways to do this depending upon the behavior you want. First you can just validate the user input before using Integer.parseInt (see http://www.javaprogrammingforums.com...tring-int.html) and if its wrong respond accordingly (warn the user, re-show the dialog, etc...). Another way is to create a custom input dialog where you validate input in-line (see How to Make Dialogs (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Swing Components) - the CustomDialog.java example). Lastly you can create a a custom JTextField that you add to a custom JOptionPane that only allows the input you want (digits) using a KeyListener to screen the input, perhaps responding with a System beep when invalid input is typed

Dear copig, can you show me how to do it based on my program?

Originally Posted by nic

Dear copig, can you show me how to do it based on my program?

I didn't post code because of the several different ways to do it, the latter two are a bit complex. So here's the first possible way in pseudo-code

 
public void someFunction(){
    String input = JOptionPane.showInputDialog(/*your dialog stuff*/);
    while ( !isDigits(input) ){
        System.out.println("Invalid Input");
         input = JOptionPane.showInputDialog(/*your dialog stuff*/);
    }
    ///deal with proper input here
}
public boolean isDigits(){
//check for proper digits (see link in my original post), return true for all digits, false otherwise
}

sorry for the wrong spelling of your name just now... err..if based on my program there it why have to use boolean ?? blur blur .... i have view the tutorial but it did not show how to make it also...