How to write a Container Listener in Java?

[Pratim]

Hi friends,
I am posting on this forum for the first time. Need your help. I am stuck while using the Container Listener. I have tried different ways for getting the result but was not succeeded. Please tell me how to write a Container Listener.?? Somebody out there would be interested in solving my problem.!!

[CodGuru]

I think that before going for the coding you should know what exactly the container listener are and when they are used.!?? I am trying to explain you in simple words. Container events are fired by a Container just after a component is added to or removed from the container. These events are for notification only when no container listener need be present for components to be successfully added or removed. Hope that you got the point that I was trying to tell you,..!!

[Viensterrr]

The following are the methods that are called when the ContainerListener Interface is used. The corresponding adapter for the ContainerListener Interface class is ContainerAdapter.

• componentAdded(ContainerEvent) - This method is called just after a component is added to the listened-to container.
• componentRemoved(ContainerEvent) - This method is called just after a component is removed from the listened-to container.

[MELTRONICS]

The following are the coding for demo's container event handling code :

public class ContainerEventDemo ... implements ContainerListener ... {
	buttonPanel = new JPanel(new GridLayout(2,2));
	buttonPanel.addContainerListener(this);
    ...
    public void componentAdded(ContainerEvent e) {
	displayMessage(" added to ", e);
    }

    public void componentRemoved(ContainerEvent e) {
	displayMessage(" removed from ", e);
    }

    void displayMessage(String action, ContainerEvent e) {
	display.append(((JButton)e.getChild()).getText()
		       + " was"
		       + action
		       + e.getContainer().getClass().getName()
		       + newline);
    }
    ...
}

[absolute55]

For creating the GUI, you can use the following code :

private static void createAndShowGUI() {

        JFrame frame = new JFrame("TrialContainerEvent");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JComponent newContentPane = new ContainerEventDemo();
        newContentPane.setOpaque(true); 
        frame.setContentPane(newContentPane);

        frame.pack();
        frame.setVisible(true);
    }