import java.awt.*;
import java.awt.event.*;
import javax.swing.JPopupMenu;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.ButtonGroup;
import javax.swing.JMenuBar;
import javax.swing.ImageIcon;

import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JFrame;

/*
 * This class adds popup menus to MenuDemo.
 */
public class PopupMenuDemo extends JFrame 
                           implements ActionListener, ItemListener {
    JTextArea output;
    JScrollPane scrollPane;
    String newline = "\n";
    JPopupMenu popup;

    public PopupMenuDemo() {
        JMenuBar menuBar;
        JMenu menu, submenu;
        JMenuItem menuItem;
        JRadioButtonMenuItem rbMenuItem;
        JCheckBoxMenuItem cbMenuItem;

        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

        //Add regular components to the window, using the default BorderLayout.
        Container contentPane = getContentPane();
        output = new JTextArea(5, 30);
        output.setEditable(false);
        scrollPane = new JScrollPane(output);
        contentPane.add(scrollPane, BorderLayout.CENTER);

        //Create the menu bar.
        menuBar = new JMenuBar();
        setJMenuBar(menuBar);

        //Build the first menu.
        menu = new JMenu("A Menu");
        menuBar.add(menu);

        //a group of JMenuItems
        menuItem = new JMenuItem("A text-only menu item");
        menuItem.addActionListener(this);
        menu.add(menuItem);
        menuItem = new JMenuItem("Both text and icon", 
                                 new ImageIcon("images/middle.gif"));
        menuItem.addActionListener(this);
        menu.add(menuItem);
        menuItem = new JMenuItem(new ImageIcon("images/middle.gif"));
        menuItem.addActionListener(this);
        menu.add(menuItem);

        //a group of radio button menu items
        menu.addSeparator();
        ButtonGroup group = new ButtonGroup();
        rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
        rbMenuItem.setSelected(true);
        group.add(rbMenuItem);
        rbMenuItem.addActionListener(this);
        menu.add(rbMenuItem);
        rbMenuItem = new JRadioButtonMenuItem("Another one");
        group.add(rbMenuItem);
        rbMenuItem.addActionListener(this);
        menu.add(rbMenuItem);

        //a group of check box menu items
        menu.addSeparator();
        cbMenuItem = new JCheckBoxMenuItem("A check box menu item");
        cbMenuItem.addItemListener(this);
        menu.add(cbMenuItem);
        cbMenuItem = new JCheckBoxMenuItem("Another one");
        cbMenuItem.addItemListener(this);
        menu.add(cbMenuItem);

        //a submenu
        menu.addSeparator();
        submenu = new JMenu("A submenu");
        menuItem = new JMenuItem("An item in the submenu");
        menuItem.addActionListener(this);
        submenu.add(menuItem);
        menuItem = new JMenuItem("Another item");
        menuItem.addActionListener(this);
        submenu.add(menuItem);
        menu.add(submenu);

        //Build second menu in the menu bar.
        menu = new JMenu("Another Menu");
        menuBar.add(menu);

	//Create the popup menu.
	popup = new JPopupMenu();
	menuItem = new JMenuItem("A popup menu item");
	menuItem.addActionListener(this);
	popup.add(menuItem);
	menuItem = new JMenuItem("Another popup menu item");
	menuItem.addActionListener(this);
	popup.add(menuItem);

	//Add listener to components that can bring up popup menus.
	MouseListener popupListener = new PopupListener();
	output.addMouseListener(popupListener);
	scrollPane.addMouseListener(popupListener);
	menuBar.addMouseListener(popupListener);
    }

    public void actionPerformed(ActionEvent e) {
        JMenuItem source = (JMenuItem)(e.getSource());
        String s = "Action event detected."
                   + newline
                   + "    Event source: " + source.getText()
                   + " (an instance of " + getClassName(source) + ")";
        output.append(s + newline);
    }

    public void itemStateChanged(ItemEvent e) {
        JMenuItem source = (JMenuItem)(e.getSource());
        String s = "Item event detected."
                   + newline
                   + "    Event source: " + source.getText()
                   + " (an instance of " + getClassName(source) + ")"
                   + newline
                   + "    New state: " 
                   + ((e.getStateChange() == ItemEvent.SELECTED) ?
                     "selected":"unselected");
        output.append(s + newline);
    }

    // Returns just the class name -- no package info.
    protected String getClassName(Object o) {
        String classString = o.getClass().getName();
        int dotIndex = classString.lastIndexOf(".");
        return classString.substring(dotIndex+1);
    }

    public static void main(String[] args) {
        PopupMenuDemo window = new PopupMenuDemo();

        window.setTitle("PopupMenuDemo");
        window.setSize(450, 260);
        window.setVisible(true);
    }

    class PopupListener extends MouseAdapter {
	public void mousePressed(MouseEvent e) {
	    maybeShowPopup(e);
	}

	public void mouseReleased(MouseEvent e) {
	    maybeShowPopup(e);
	}

	private void maybeShowPopup(MouseEvent e) {
	    if (e.isPopupTrigger()) {
		popup.show(e.getComponent(),
			   e.getX(), e.getY());
	    }
	}
    }
}