/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.beans;import java.awt.*;import java.awt.event.*;import java.util.*;/** * This JavaBean displays a multi-line message and up to three buttons.  It * fires an AnswerEvent when the user clicks on one of the buttons **/public class YesNoPanel extends Panel {    // Properties of the bean.    protected String messageText;  // The message to display    protected Alignment alignment; // The alignment of the message    protected String yesLabel;     // Text for the yes, no, & cancel buttons    protected String noLabel;    protected String cancelLabel;        // Internal components of the panel    protected MultiLineLabel message;    protected Button yes, no, cancel;        /** The no-argument bean constructor, with default property values */    public YesNoPanel() { this("Your\nMessage\nHere"); }    public YesNoPanel(String messageText) { 	this(messageText, Alignment.LEFT, "Yes", "No", "Cancel");    }        /** A constructor for programmers using this class "by hand" */    public YesNoPanel(String messageText, Alignment alignment,		      String yesLabel, String noLabel, String cancelLabel)     {	// Create the components for this panel	setLayout(new BorderLayout(15, 15));		// Put the message label in the middle of the window.	message = new MultiLineLabel(messageText, 20, 20, alignment);	add(message, BorderLayout.CENTER);		// Create a panel for the Panel buttons and put it at the bottom	// of the Panel.  Specify a FlowLayout layout manager for it.	Panel buttonbox = new Panel();	buttonbox.setLayout(new FlowLayout(FlowLayout.CENTER, 25, 15));	add(buttonbox, BorderLayout.SOUTH);		// Create each specified button, specifying the action listener	// and action command for each, and adding them to the buttonbox	yes = new Button();                   // Create buttons	no = new Button();	cancel = new Button();	// Add the buttons to the button box	buttonbox.add(yes);	buttonbox.add(no);	buttonbox.add(cancel);	// Register listeners for each button	yes.addActionListener(new ActionListener() {		public void actionPerformed(ActionEvent e) {		    fireEvent(new AnswerEvent(YesNoPanel.this,					      AnswerEvent.YES));		}	    });	no.addActionListener(new ActionListener() { 		public void actionPerformed(ActionEvent e) {		    fireEvent(new AnswerEvent(YesNoPanel.this,					      AnswerEvent.NO));			      }	    });	cancel.addActionListener(new ActionListener() { 		public void actionPerformed(ActionEvent e) {		    fireEvent(new AnswerEvent(YesNoPanel.this,					      AnswerEvent.CANCEL));		}	    });		// Now call property setter methods to set the message and button	// components to contain the right text	setMessageText(messageText);	setAlignment(alignment);	setYesLabel(yesLabel);	setNoLabel(noLabel);	setCancelLabel(cancelLabel);    }        // Methods to query all of the bean properties.    public String getMessageText() { return messageText; }    public Alignment getAlignment() { return alignment; }    public String getYesLabel() { return yesLabel; }    public String getNoLabel() { return noLabel; }    public String getCancelLabel() { return cancelLabel; }        // Methods to set all of the bean properties.    public void setMessageText(String messageText) {	this.messageText = messageText;	message.setLabel(messageText);	validate();    }    public void setAlignment(Alignment alignment) {	this.alignment = alignment;	message.setAlignment(alignment);    }    public void setYesLabel(String l) {	yesLabel = l;	yes.setLabel(l);	yes.setVisible((l != null) && (l.length() > 0));	validate();    }    public void setNoLabel(String l) {	noLabel = l;	no.setLabel(l);	no.setVisible((l != null) && (l.length() > 0));	validate();    }    public void setCancelLabel(String l) {	cancelLabel = l;	cancel.setLabel(l);	cancel.setVisible((l != null) && (l.length() > 0));	validate();    }    public void setFont(Font f) {	super.setFont(f);    // Invoke the superclass method	message.setFont(f);  	yes.setFont(f);	no.setFont(f);	cancel.setFont(f);	validate();    }        /** This field holds a list of registered ActionListeners. */    protected Vector listeners = new Vector();        /** Register an action listener to be notified when a button is pressed */    public void addAnswerListener(AnswerListener l) {	listeners.addElement(l);    }        /** Remove an Answer listener from our list of interested listeners */    public void removeAnswerListener(AnswerListener l) {	listeners.removeElement(l);    }        /** Send an event to all registered listeners */    public void fireEvent(AnswerEvent e) {	// Make a copy of the list and fire the events using that copy.	// This means that listeners can be added or removed from the original	// list in response to this event.  We ought to be able to just use an	// enumeration for the vector, but that doesn't actually copy the list.	Vector list = (Vector) listeners.clone();	for(int i = 0; i < list.size(); i++) {	    AnswerListener listener = (AnswerListener)list.elementAt(i);	    switch(e.getID()) {	    case AnswerEvent.YES: listener.yes(e); break;	    case AnswerEvent.NO:  listener.no(e); break;	    case AnswerEvent.CANCEL: listener.cancel(e); break;	    }	}    }        /** A main method that demonstrates the class */    public static void main(String[] args) {	// Create an instance of InfoPanel, with title and message specified:	YesNoPanel p = new YesNoPanel("Do you really want to quit?");	// Register an action listener for the Panel.  This one just prints	// the results out to the console.	p.addAnswerListener(new AnswerListener() {		public void yes(AnswerEvent e) { System.exit(0); }		public void no(AnswerEvent e) { System.out.println("No"); }		public void cancel(AnswerEvent e) {                    System.out.println("Cancel");                }	    });		Frame f = new Frame();	f.add(p);	f.pack();	f.setVisible(true);    }}