KeyEvent not being generated by JFrame java?

I have a java program with a JFrame and 3 JButtons in it. I have added a keylistener to jframe. When i run the program a jframe window is opened and the first button is selected by default. My problem is that a KeyEvent is not being generated by this JFrame. Now, besides adding a KeyListener to th开发者_运维知识库e jframe, i also added a KeyListener to the buttons. Now the keyevent is being generated by the buttons.

How do I make the JFrame generate KeyEvent instead of the JButton generating them ??

Actually, my main purpose is building keyboard shortcuts for the buttons.

Have a look here How to Use Key Bindings.
An alternative to keylistener.

Here is a little Example it has a Button with focus and process a KeyEvent (F2).
On F2-clicked the Key-Binding process a ButtonClick which performed a System.out print.

public class Example {
    static public void main( String[] s ) {
        EventQueue.invokeLater( new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.getContentPane().setLayout( new BorderLayout() );
                frame.setBounds( 50, 50, 600, 600 );
                frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
                final JButton button = new JButton( new AbstractAction("MyButton") {
                    @Override
                    public void actionPerformed( ActionEvent e ) {
                        System.out.println("Button Clicked");
                    }
                });
                frame.getContentPane().add( button );
                frame.getRootPane().setDefaultButton( button );

                KeyStroke f2 = KeyStroke.getKeyStroke("F2");
                frame.getRootPane().getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(f2, "clickButton");
                frame.getRootPane().getActionMap().put("clickButton", new AbstractAction() {
                    @Override
                    public void actionPerformed( ActionEvent e ) {
                        button.doClick();
                    }
                });
                frame.setVisible( true );
                // the Button has the focus
                button.requestFocus();
                // generate a KeyEvent 'F2' 
                KeyboardFocusManager.getCurrentKeyboardFocusManager().dispatchKeyEvent( new KeyEvent( frame, KeyEvent.KEY_PRESSED, 0, f2.getModifiers(), f2.getKeyCode(), f2.getKeyChar() ) );
            }
        });
    }
}

The key event is called on the currently focused component (which is usually not the JFrame)