What is the Popup class used for

Question

I always thought that a Popup should have some basic functionality, such as the pupup should close when:
a) the escape key is pressed
b) the popup loses focus
The popup class provides none of the above functionality and in     fact seems to require some obscure code to
even get the keyboard focus to work properly.
Using a JWindow seems to provide the same functionality as a Popup.
JPopupMenu seems to support both of the above requirements.
Run the following program:
a) click on each of the buttons
b) click on an empty part of the frame
It appears to me that whenever you need a "popup" you should use a JPopupMenu.
Is the Popup class good for anything? Does it provide any functionality that I am not aware of?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class PopupTest extends JFrame
     String[] numbers = { "one", "two", "three", "four", "five" };
     public PopupTest()
          getContentPane().setLayout( new FlowLayout() );
          JButton popup = new JButton("Popup as Popup");
          popup.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    popupPopup(e);
          getContentPane().add(popup);
          JButton window = new JButton("Window as Popup");
          window.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    windowPopup(e);
          getContentPane().add(window);
          JButton menu = new JButton("PopupMenu as Popup");
          menu.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent e)
                    menuPopup(e);
          getContentPane().add(menu);
     private void popupPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          PopupFactory factory = PopupFactory.getSharedInstance();
          Popup popup = factory.getPopup(this, list, getLocation().x, getLocation().y);
          popup.show();
          Window window = SwingUtilities.windowForComponent(list);
          if (window != null)
               window.setFocusableWindowState(true);
          KeyboardFocusManager.getCurrentKeyboardFocusManager().focusNextComponent(list);
     private void windowPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          JWindow window = new JWindow(this);
          window.getContentPane().add(list);
          window.pack();
          window.setVisible(true);
          window.setLocation(getLocation().x + 200, getLocation().y);
     private void menuPopup(ActionEvent e)
          JList list = new JList(numbers);
          list.setSelectedIndex(0);
          Component c = (Component)e.getSource();
          JPopupMenu menu = new JPopupMenu();
          menu.add(list);
          menu.show(c, 0, 0);
          list.requestFocusInWindow();
     public static void main(String[] args)
          PopupTest frame = new PopupTest();
          frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
          frame.setSize(500, 200);
          frame.setLocationRelativeTo( null );
          frame.show();
}

Answer 1

you'd use Popup like JPopupMenu does, via a PopupFactoryYes you can get the Popu from the PopupFactory, but I think you are missing the point of my question. Popup has two methods, hide/show. It provides no other funtionality. I must write code to handle the escapce key and close the popup when it loses focus.
When I use a JPopupMenu and add a component to the menu, it appears to add some listeners to the component to handle the escape key and loss of focus.
I think it's safe to say that you're right when you say that it's preferable to use
JPopupMenu (my experience as well).That was my conclusion, but I was just wondering it I was missing anything.
It turns out that there are used in tooltips which, by essence, don't need any
input from the user (whether keyboard or mouse) I guess thats what I was missing, only use a Popup in tooltip type situations.