Textfeld begrenzen

/*
 * Created on 04.01.2006
 * 
 * @author Benjamin Ferrari
 */


import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;


public class SwingTest extends JPanel {


  private static final int LIMIT = 20;

  private JTextField textField = new JTextField(50);


  
  public SwingTest() {
    this.add(this.textField);
    this.textField.setDocument(new PlainDocument() {


      public void insertString(int offset, String str, AttributeSet attr)
          throws BadLocationException {
        if ((getLength() + str.length()) <= LIMIT) {
          super.insertString(offset, str, attr);
        }
      }


    });
  }


  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.add(new SwingTest());
    frame.pack();
    frame.setVisible(true);
  }


}