JTextField, Zeichenzahl begrenzen

Im folgenden Code-Beisiel werden maximal 10 akzeptiert:

package com.sowas.snippets.jtextfield;
 
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
import javax.swing.text.AttributeSet;
import java.math.BigDecimal;
 
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
 
public class TextFieldDemo {
   public static void main (final String [] ignored){
      JFrame frame = new JFrame ("Numerisches JTextField");
      JTextField tf = new JTextField();
      Document doc = tf.getDocument();
      ((AbstractDocument) doc).setDocumentFilter(new DocumentNumberFilter(10));
      frame.getContentPane().setLayout (new BorderLayout (0,0));
      frame.getContentPane().add(tv, BorderLayout.NORTH);
      frame.pack ();
      frame.setVisible (true);
   }
}