import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 *  This class will help you take control of the frame closing process by
 *  providing a WindowListener with some common features that might be used
 *  when closing an application. That is you can:
 *	<ul>
 *  <li>display an application closing confirmation message which will give
 *    the user a chance to cancel the close request
 *  <li>invoke a provide Action. This action might be used to save the state
 *    of the application for the next time it is used.
 *  </ul>
 *
 *  This class will invoke the setDefaultCloseOperation(...) method with an
 *  appropriate value. The default will be set to EXIT_ON_CLOSE. The default
 *  can be changed by invoking the setDisoseOnClose() method with "true", in
 *  which case DISPOSE_ON_CLOSE will be used. This value will be set to
 *  DO_NOTHING_ON_CLOSE if the user does not confirm the application closing
 *  message. Finally, the close action is free to set this property to any
 *  value.
 */
public class CloseListener extends WindowAdapter
{
	private String message;
	private String title;
	private Action closeAction;
	private boolean disposeOnClose = false;

	/**
	 *  Display a confirmation message upon closing the application
	 *
	 *  @param message  the confirmation message
	 *  @param title    the text used for the title bar of the dialog
	 */
	public CloseListener(String message, String title)
	{
		this(message, title, null);
	}

	/**
	 *  Specify an Action to be invoked upon closing the application.
	 *
	 *  @param closeAction  the Action to be invoked upon closing the application
	 */
	public CloseListener(Action closeAction)
	{
		this(null, null, closeAction);
	}

	/**
	 *  Display a confirmation message upon closing the application and
	 *	and invoke a closing action.
	 *
	 *  @param message      the confirmation message
	 *  @param title        the text used for the title bar of the dialog
	 *  @param closeAction  the Action to be invoked upon closing the application
	 */
	public CloseListener(String message, String title, Action closeAction)
	{
		this.message = message;
		this.title = title;
		this.closeAction = closeAction;
	}

	/**
	 *  Set the default close operation to be dispose on close. Typically would
	 *  be used in a multi frame application. This way only when the last frame
	 *  is closed will the JVM be shut down.
	 *
	 *  @param disposeOnClose  true for DISPOSE_ON_CLOSE, false for EXIT_ON_CLOSE
	 */
	public void setDisposeOnClose(boolean disposeOnClose)
	{
		this.disposeOnClose = disposeOnClose;
	}

	@Override
	public void windowClosing(WindowEvent e)
	{
		JFrame frame = (JFrame)e.getComponent();

		//  Confirm with the user to close the frame

		if (! confirmWindowClosing(frame))
		{
			frame.setDefaultCloseOperation( JFrame.DO_NOTHING_ON_CLOSE );
			return;
		}

		//  Set the close option. Setting it here allows the close action to
		//  prevent the window from closing by resetting the close option to
		//  DO_NOTHING_ON_CLOSE.

		if (disposeOnClose)
			frame.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
		else
			frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

		//  Confirmation received, so do the exit processing

		if (closeAction != null)
		{
			ActionEvent ae = new ActionEvent(frame, ActionEvent.ACTION_PERFORMED, "");
			closeAction.actionPerformed( ae );
		}
	}

	private boolean confirmWindowClosing(JFrame frame)
	{
		if (message == null) return true;

		int result = JOptionPane.showConfirmDialog(
			frame,
			message,
			title,
			JOptionPane.YES_NO_OPTION);

		return (result == JOptionPane.YES_OPTION) ? true : false;
	}
}