JComboBox cann't add KeyListener? Why?

Question

There is a fragment:
JComboBox cBox = new JComboBox();
cBox..setEditable(true);
cBox.addKeyListener(new KeyAdapter(){
               @Override
               public void keyPressed(KeyEvent e) {
                    System.out.println(e.getKeyChar());
Whatever I press which key,the console print nothing,why?
And I want to restrict the user's input through this way,any better ideas?
thanks for ur help!

Answer 1

For an editable JComboBox, you need to add the KeyListener to the editor component, something like this:
comboBox.getEditor().getEditorComponent().addKeyListener(...)
And I want to restrict the user's input through this way,any better ideas?Have a look at the Swing tutorial on [url http://java.sun.com/docs/books/tutorial/uiswing/components/generaltext.html#filter]Implementing a Document Filter. Next, get the editor component for the JComboBox (which is a JTextField), and add the Document Filter to it.