Java JTextField update text via Document

import java.awt.BorderLayout;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.BadLocationException;
import javax.swing.text.JTextComponent;

class MyKeyListener extends KeyAdapter {
   public void keyTyped(KeyEvent evt) {
      JTextComponent c = (JTextComponent) evt.getSource();
      char ch = evt.getKeyChar();

      if (Character.isLowerCase(ch) == false) {
         return;//from  w ww  .  ja va2 s .co m
      }
      try {
         c.getDocument().insertString(c.getCaretPosition(), "" + Character.toUpperCase(ch), null);
         evt.consume();
      } catch (BadLocationException e) {
      }
   }
}

public class Main {
   public static void main(String[] argv) throws Exception {
      JTextField component = new JTextField();
      component.addKeyListener(new MyKeyListener());

      JFrame f = new JFrame();
      f.add(component, BorderLayout.NORTH);
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.setSize(300, 300);
      f.setVisible(true);
   }
}