Question

I created a component based on a JPanel that contains a textfield and a checkbox. Since I use it as component and put it around in other panels I’d like to be able to set a KeyPressed event for the panel. Obiouvsly this doesn’t work as the keyPressed events fire for the inner textfield. Is it there a way to propagate them to the JPanel as it was receiving them instead of the textfield? I tried with handleEvent but it doesn’t even compile.

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Let’s clarify the question. I created this big element containing a textfield. Now a want to use this element in another and I want to set the OTHER ONE as the listener. So there is the JPanel between. That’s the problem.

Answer 1

You can use javax.swing.event.EventListenerList in the JPanel containing the JTextField, and create a addKeyListener public method.

import javax.swing.event.EventListenerList;

public static class TestPanel extends JPanel implements KeyListener{  
    private JTextField text;
    private EventListenerList listenerList = new EventListenerList();

    TestPanel(){
        text = new JTextField();
        text.addKeyListener(this);
    }

    public void keyPressed(KeyEvent e){
        //doesn't create a new array, used for performance reasons 
        Object[] listeners = listenerList.getListenerList();
        //Array of pairs listeners[i] is Class, listeners[i + 1] is EventListener
        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i] == KeyListener.class) {
                ((KeyListener)listeners[i+1]).keyPressed(e);
            }          
        }
    }

    public void addKeyListener(KeyListener l) {
        listenerList.add(KeyListener.class, l);
    }

    public void keyReleased(KeyEvent e){
      //idem as for keyPressed           
    }

    public void keyTyped(KeyEvent e){
      //idem as for keyPressed
    }
}