Re: Keystroke validation in JTextField

icogs wrote:


You don't want to do it that way with JComponents. Use a Document to
control those sorts of things. Look at PlainDocument in the docs and
see an example below of how to implement a document that only allows
upper case letters.

//
//
// UpperCaseDocument
//
//

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class UpperCaseDocument extends PlainDocument {
     int length = 0;

     public UpperCaseDocument() {
     }

     public UpperCaseDocument(int length) {
         this.length = length;
     }

     public void insertString(int offs, String str, AttributeSet a)
      throws BadLocationException {
         if (str == null) {
             return;
         }
         if (length > 0)
             if (str.length() + getLength() > length)
                 str = str.substring(0,length - getLength());
         char[] upper = str.toCharArray();
         for (int i = 0; i < upper.length; i++)
             upper[i] = Character.toUpperCase(upper[i]);
         super.insertString(offs, new String(upper), a);
     }
}

--

Knute Johnson
email s/nospam/knute/