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For the Swing gurus

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Join Date: Nov 2004

Posts: 6,143

Reputation: jwenting is just really nice

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jwenting

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duckman

For the Swing gurus

Aug 4th, 2005

yes, there's an area of Java I'm almost a complete novice in (so far, I'm going full steam ahead :cheesy: ).

I've the following code to filter out non-numeric input from a JTextField (which is meant to contain a timeout interval in minutes, that's why).

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
    private void dumpNonNumericInput(KeyEvent e) {
        char input = e.getKeyChar();
        String oldText = ((JTextField)e.getSource()).getText();
        if (input != KeyEvent.VK_BACK_SPACE && input != KeyEvent.VK_DELETE &&
            (input < '0' || input > '9')) {
            JOptionPane.showMessageDialog(this, "Numeric input required",
                                          "Input error",
                                          JOptionPane.ERROR_MESSAGE);
            e.consume();
            ((JTextField)e.getSource()).setText(oldText);
 
        }
    }
    private void dumpNonNumericInput(KeyEvent e) {
        char input = e.getKeyChar();
        String oldText = ((JTextField)e.getSource()).getText();
        if (input != KeyEvent.VK_BACK_SPACE && input != KeyEvent.VK_DELETE &&
            (input < '0' || input > '9')) {
            JOptionPane.showMessageDialog(this, "Numeric input required",
                                          "Input error",
                                          JOptionPane.ERROR_MESSAGE);
            e.consume();
            ((JTextField)e.getSource()).setText(oldText);

        }
    }

This method works like a charm, that's not the problem.
The problem is that is I remove the error message popup (just the showMessageDialog command) the method no longer removes the faulty input either.
I THINK it's something to do with Swing thread timing, but I'm not sure.
Neither do I know how to cure this, which is more important at the moment as I'd rather not have that popup appear every time someone makes a typo.

I could probably subclass JTextField but that may be more trouble than it's worth.

As people are clearly allowed to attack me but I'm not allowed to defend myself, I no longer post to this site.

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Join Date: Aug 2005

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ProFreelance ProFreelance is offline

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Newbie Poster

Re: For the Swing gurus

Aug 5th, 2005

Can you do it with a try catch statement?

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Join Date: Feb 2005

Posts: 46

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Gink

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Light Poster

Re: For the Swing gurus

Aug 5th, 2005

A better alternative would be to disable text input altogether (call setEditable(false) on the text field. This deals with the problem of people putting in garbage input. Then all you need to do is use regular expression on the character that was input. Then use reg exp for input
if(stringvar.matches("\\d")){}

Not sure why removing a showMessageDialog would have any effect on the following code.

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Join Date: Jun 2005

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cheenu78

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Re: For the Swing gurus

Aug 5th, 2005

hi jwenting,

I have attached a Textfield which takes number of columns(maximum number of characters that the textfield can take) as parameter. If you use the usual textfields with keylistener, you can set illegal characters programattically. This textfield(one attached) does not allow illegal characters either by entry or progammatically. You can run the program attached and check out and tell me whether it was useful.

TextFieldDemo is the one with main method.

I am not sure whether this is exactly your requirement

regards
Srinivas

Attached Files

	NumericTextField.java (1.7 KB, 9 views)
	TextFieldDemo.java (280 Bytes, 6 views)

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-Sam Keen, from To Love and Be Loved

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Join Date: Nov 2004

Posts: 6,143

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jwenting

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duckman

Re: For the Swing gurus

Aug 5th, 2005

Cheers, I'll give it a look.

Gink, the idea is to allow only certain input. If it were readonly I'd have used a label or something else instead

As people are clearly allowed to attack me but I'm not allowed to defend myself, I no longer post to this site.

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Join Date: Feb 2005

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Gink

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Light Poster

Re: For the Swing gurus

Aug 5th, 2005

Im not suggesting to make it read-only. What im saying is add a keylistener and whenever the user presses a key just update the textfield accordingly. The only reason I said uneditable is to prevent people from typing in characters that the keylistener doesnt respond to. It is still editable by the program, and the user wont know it's uneditable.

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Join Date: Nov 2004

Posts: 6,143

Reputation: jwenting is just really nice

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jwenting

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duckman

Re: For the Swing gurus

Aug 5th, 2005

ah.

Found I can't catch shortcut keys (like Alt-T, Alt-X, etc.) using this system so I abandoned it.
Instead I now validate the field when it's value is read out instead of when it's input and give an error then.

As people are clearly allowed to attack me but I'm not allowed to defend myself, I no longer post to this site.

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Join Date: Jun 2004

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Postaholic

Re: For the Swing gurus

Aug 5th, 2005

Why not a boolean check method?

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
public boolean check(String text)
{
   try
   {
        Double.parseDouble(text);
        return true;
   }
   catch
   {
       JOptionPane.showMessageDialog(null,"Numeric crap only");
       return false;
   }
   return false;
}
public boolean check(String text)
{
   try
   {
        Double.parseDouble(text);
        return true;
   }
   catch
   {
       JOptionPane.showMessageDialog(null,"Numeric crap only");
       return false;
   }
   return false;
}

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Join Date: Nov 2004

Posts: 6,143

Reputation: jwenting is just really nice

Solved Threads: 213

jwenting

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duckman

Re: For the Swing gurus

Aug 5th, 2005

yes, something like that

Thought to be a tad more friendly with my users though :p

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
        try {
            Integer.parseInt(timeout.getText());
        } catch (NumberFormatException ex) {
            JOptionPane.showMessageDialog(this,
                                          "Timeout interval must be a number",
                                          "Input error",
                                          JOptionPane.ERROR_MESSAGE);
            return;
        }
        try {
            Integer.parseInt(timeout.getText());
        } catch (NumberFormatException ex) {
            JOptionPane.showMessageDialog(this,
                                          "Timeout interval must be a number",
                                          "Input error",
                                          JOptionPane.ERROR_MESSAGE);
            return;
        }