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	/*
	* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/



	package javax.swing;



	import java.util.*;
	import java.util.concurrent.atomic.AtomicBoolean;
	import java.util.concurrent.locks.*;
	import java.awt.*;
	import java.awt.event.*;
	import java.io.Serializable;
	import java.io.*;
	import java.security.AccessControlContext;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import javax.swing.event.EventListenerList;



	/**
	* Fires one or more {@code ActionEvent}s at specified
	* intervals. An example use is an animation object that uses a
	* <code>Timer</code> as the trigger for drawing its frames.
	*<p>
	* Setting up a timer
	* involves creating a <code>Timer</code> object,
	* registering one or more action listeners on it,
	* and starting the timer using
	* the <code>start</code> method.
	* For example,
	* the following code creates and starts a timer
	* that fires an action event once per second
	* (as specified by the first argument to the <code>Timer</code> constructor).
	* The second argument to the <code>Timer</code> constructor
	* specifies a listener to receive the timer's action events.
	*
	*<pre>
	* int delay = 1000; //milliseconds
	* ActionListener taskPerformer = new ActionListener() {
	* public void actionPerformed(ActionEvent evt) {
	* <em>//...Perform a task...</em>
	* }
	* };
	* new Timer(delay, taskPerformer).start();</pre>
	*
	* <p>
	* {@code Timers} are constructed by specifying both a delay parameter
	* and an {@code ActionListener}. The delay parameter is used
	* to set both the initial delay and the delay between event
	* firing, in milliseconds. Once the timer has been started,
	* it waits for the initial delay before firing its
	* first <code>ActionEvent</code> to registered listeners.
	* After this first event, it continues to fire events
	* every time the between-event delay has elapsed, until it
	* is stopped.
	* <p>
	* After construction, the initial delay and the between-event
	* delay can be changed independently, and additional
	* <code>ActionListeners</code> may be added.
	* <p>
	* If you want the timer to fire only the first time and then stop,
	* invoke <code>setRepeats(false)</code> on the timer.
	* <p>
	* Although all <code>Timer</code>s perform their waiting
	* using a single, shared thread
	* (created by the first <code>Timer</code> object that executes),
	* the action event handlers for <code>Timer</code>s
	* execute on another thread -- the event-dispatching thread.
	* This means that the action handlers for <code>Timer</code>s
	* can safely perform operations on Swing components.
	* However, it also means that the handlers must execute quickly
	* to keep the GUI responsive.
	*
	* <p>
	* In v 1.3, another <code>Timer</code> class was added
	* to the Java platform: <code>java.util.Timer</code>.
	* Both it and <code>javax.swing.Timer</code>
	* provide the same basic functionality,
	* but <code>java.util.Timer</code>
	* is more general and has more features.
	* The <code>javax.swing.Timer</code> has two features
	* that can make it a little easier to use with GUIs.
	* First, its event handling metaphor is familiar to GUI programmers
	* and can make dealing with the event-dispatching thread
	* a bit simpler.
	* Second, its
	* automatic thread sharing means that you don't have to
	* take special steps to avoid spawning
	* too many threads.
	* Instead, your timer uses the same thread
	* used to make cursors blink,
	* tool tips appear,
	* and so on.
	*
	* <p>
	* You can find further documentation
	* and several examples of using timers by visiting
	* <a href="https://docs.oracle.com/javase/tutorial/uiswing/misc/timer.html"
	* target = "_top">How to Use Timers</a>,
	* a section in <em>The Java Tutorial.</em>
	* For more examples and help in choosing between
	* this <code>Timer</code> class and
	* <code>java.util.Timer</code>,
	* see
	* <a href="http://java.sun.com/products/jfc/tsc/articles/timer/"
	* target="_top">Using Timers in Swing Applications</a>,
	* an article in <em>The Swing Connection.</em>
	* <p>
	* <strong>Warning:</strong>
	* Serialized objects of this class will not be compatible with
	* future Swing releases. The current serialization support is
	* appropriate for short term storage or RMI between applications running
	* the same version of Swing. As of 1.4, support for long term storage
	* of all JavaBeans™
	* has been added to the <code>java.beans</code> package.
	* Please see {@link java.beans.XMLEncoder}.
	*
	* @see java.util.Timer <code>java.util.Timer</code>
	*
	*
	* @author Dave Moore
	*/
	@SuppressWarnings("serial")
	public class Timer implements Serializable
	{
	/*
	* NOTE: all fields need to be handled in readResolve
	*/

	protected EventListenerList listenerList = new EventListenerList();

	// The following field strives to maintain the following:
	// If coalesce is true, only allow one Runnable to be queued on the
	// EventQueue and be pending (ie in the process of notifying the
	// ActionListener). If we didn't do this it would allow for a
	// situation where the app is taking too long to process the
	// actionPerformed, and thus we'ld end up queing a bunch of Runnables
	// and the app would never return: not good. This of course implies
	// you can get dropped events, but such is life.
	// notify is used to indicate if the ActionListener can be notified, when
	// the Runnable is processed if this is true it will notify the listeners.
	// notify is set to true when the Timer fires and the Runnable is queued.
	// It will be set to false after notifying the listeners (if coalesce is
	// true) or if the developer invokes stop.
	private transient final AtomicBoolean notify = new AtomicBoolean(false);

	private volatile int initialDelay, delay;
	private volatile boolean repeats = true, coalesce = true;

	private transient final Runnable doPostEvent;

	private static volatile boolean logTimers;

	private transient final Lock lock = new ReentrantLock();

	// This field is maintained by TimerQueue.
	// eventQueued can also be reset by the TimerQueue, but will only ever
	// happen in applet case when TimerQueues thread is destroyed.
	// access to this field is synchronized on getLock() lock.
	transient TimerQueue.DelayedTimer delayedTimer = null;

	private volatile String actionCommand;

	/**
	* Creates a {@code Timer} and initializes both the initial delay and
	* between-event delay to {@code delay} milliseconds. If {@code delay}
	* is less than or equal to zero, the timer fires as soon as it
	* is started. If <code>listener</code> is not <code>null</code>,
	* it's registered as an action listener on the timer.
	*
	* @param delay milliseconds for the initial and between-event delay
	* @param listener an initial listener; can be <code>null</code>
	*
	* @see #addActionListener
	* @see #setInitialDelay
	* @see #setRepeats
	*/
	public Timer(int delay, ActionListener listener) {
	super();
	this.delay = delay;
	this.initialDelay = delay;

	doPostEvent = new DoPostEvent();

	if (listener != null) {
	addActionListener(listener);
	}
	}

	/*
	* The timer's AccessControlContext.
	*/
	private transient volatile AccessControlContext acc =
	AccessController.getContext();

	/**
	* Returns the acc this timer was constructed with.
	*/
	final AccessControlContext getAccessControlContext() {
	if (acc == null) {
	throw new SecurityException(
	"Timer is missing AccessControlContext");
	}
	return acc;
	}

	/**
	* DoPostEvent is a runnable class that fires actionEvents to
	* the listeners on the EventDispatchThread, via invokeLater.
	* @see Timer#post
	*/
	class DoPostEvent implements Runnable
	{
	public void run() {
	if (logTimers) {
	System.out.println("Timer ringing: " + Timer.this);
	}
	if(notify.get()) {
	fireActionPerformed(new ActionEvent(Timer.this, 0, getActionCommand(),
	System.currentTimeMillis(),
	0));
	if (coalesce) {
	cancelEvent();
	}
	}
	}

	Timer getTimer() {
	return Timer.this;
	}
	}

	/**
	* Adds an action listener to the <code>Timer</code>.
	*
	* @param listener the listener to add
	*
	* @see #Timer
	*/
	public void addActionListener(ActionListener listener) {
	listenerList.add(ActionListener.class, listener);
	}


	/**
	* Removes the specified action listener from the <code>Timer</code>.
	*
	* @param listener the listener to remove
	*/
	public void removeActionListener(ActionListener listener) {
	listenerList.remove(ActionListener.class, listener);
	}


	/**
	* Returns an array of all the action listeners registered
	* on this timer.
	*
	* @return all of the timer's <code>ActionListener</code>s or an empty
	* array if no action listeners are currently registered
	*
	* @see #addActionListener
	* @see #removeActionListener
	*
	* @since 1.4
	*/
	public ActionListener[] getActionListeners() {
	return listenerList.getListeners(ActionListener.class);
	}


	/**
	* Notifies all listeners that have registered interest for
	* notification on this event type.
	*
	* @param e the action event to fire
	* @see EventListenerList
	*/
	protected void fireActionPerformed(ActionEvent e) {
	// Guaranteed to return a non-null array
	Object[] listeners = listenerList.getListenerList();

	// Process the listeners last to first, notifying
	// those that are interested in this event
	for (int i=listeners.length-2; i>=0; i-=2) {
	if (listeners[i]==ActionListener.class) {
	((ActionListener)listeners[i+1]).actionPerformed(e);
	}
	}
	}

	/**
	* Returns an array of all the objects currently registered as
	* <code><em>Foo</em>Listener</code>s
	* upon this <code>Timer</code>.
	* <code><em>Foo</em>Listener</code>s
	* are registered using the <code>add<em>Foo</em>Listener</code> method.
	* <p>
	* You can specify the <code>listenerType</code> argument
	* with a class literal, such as <code><em>Foo</em>Listener.class</code>.
	* For example, you can query a <code>Timer</code>
	* instance <code>t</code>
	* for its action listeners
	* with the following code:
	*
	* <pre>ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class));</pre>
	*
	* If no such listeners exist,
	* this method returns an empty array.
	*
	* @param listenerType the type of listeners requested;
	* this parameter should specify an interface
	* that descends from <code>java.util.EventListener</code>
	* @return an array of all objects registered as
	* <code><em>Foo</em>Listener</code>s
	* on this timer,
	* or an empty array if no such
	* listeners have been added
	* @exception ClassCastException if <code>listenerType</code> doesn't
	* specify a class or interface that implements
	* <code>java.util.EventListener</code>
	*
	* @see #getActionListeners
	* @see #addActionListener
	* @see #removeActionListener
	*
	* @since 1.3
	*/
	public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
	return listenerList.getListeners(listenerType);
	}

	/**
	* Returns the timer queue.
	*/
	private TimerQueue timerQueue() {
	return TimerQueue.sharedInstance();
	}


	/**
	* Enables or disables the timer log. When enabled, a message
	* is posted to <code>System.out</code> whenever the timer goes off.
	*
	* @param flag <code>true</code> to enable logging
	* @see #getLogTimers
	*/
	public static void setLogTimers(boolean flag) {
	logTimers = flag;
	}


	/**
	* Returns <code>true</code> if logging is enabled.
	*
	* @return <code>true</code> if logging is enabled; otherwise, false
	* @see #setLogTimers
	*/
	public static boolean getLogTimers() {
	return logTimers;
	}


	/**
	* Sets the <code>Timer</code>'s between-event delay, the number of milliseconds
	* between successive action events. This does not affect the initial delay
	* property, which can be set by the {@code setInitialDelay} method.
	*
	* @param delay the delay in milliseconds
	* @see #setInitialDelay
	*/
	public void setDelay(int delay) {
	if (delay < 0) {
	throw new IllegalArgumentException("Invalid delay: " + delay);
	}
	else {
	this.delay = delay;
	}
	}


	/**
	* Returns the delay, in milliseconds,
	* between firings of action events.
	*
	* @see #setDelay
	* @see #getInitialDelay
	*/
	public int getDelay() {
	return delay;
	}


	/**
	* Sets the <code>Timer</code>'s initial delay, the time
	* in milliseconds to wait after the timer is started
	* before firing the first event. Upon construction, this
	* is set to be the same as the between-event delay,
	* but then its value is independent and remains unaffected
	* by changes to the between-event delay.
	*
	* @param initialDelay the initial delay, in milliseconds
	* @see #setDelay
	*/
	public void setInitialDelay(int initialDelay) {
	if (initialDelay < 0) {
	throw new IllegalArgumentException("Invalid initial delay: " +
	initialDelay);
	}
	else {
	this.initialDelay = initialDelay;
	}
	}


	/**
	* Returns the <code>Timer</code>'s initial delay.
	*
	* @see #setInitialDelay
	* @see #setDelay
	*/
	public int getInitialDelay() {
	return initialDelay;
	}


	/**
	* If <code>flag</code> is <code>false</code>,
	* instructs the <code>Timer</code> to send only one
	* action event to its listeners.
	*
	* @param flag specify <code>false</code> to make the timer
	* stop after sending its first action event
	*/
	public void setRepeats(boolean flag) {
	repeats = flag;
	}


	/**
	* Returns <code>true</code> (the default)
	* if the <code>Timer</code> will send
	* an action event
	* to its listeners multiple times.
	*
	* @see #setRepeats
	*/
	public boolean isRepeats() {
	return repeats;
	}


	/**
	* Sets whether the <code>Timer</code> coalesces multiple pending
	* <code>ActionEvent</code> firings.
	* A busy application may not be able
	* to keep up with a <code>Timer</code>'s event generation,
	* causing multiple
	* action events to be queued. When processed,
	* the application sends these events one after the other, causing the
	* <code>Timer</code>'s listeners to receive a sequence of
	* events with no delay between them. Coalescing avoids this situation
	* by reducing multiple pending events to a single event.
	* <code>Timer</code>s
	* coalesce events by default.
	*
	* @param flag specify <code>false</code> to turn off coalescing
	*/
	public void setCoalesce(boolean flag) {
	boolean old = coalesce;
	coalesce = flag;
	if (!old && coalesce) {
	// We must do this as otherwise if the Timer once notified
	// in !coalese mode notify will be stuck to true and never
	// become false.
	cancelEvent();
	}
	}


	/**
	* Returns <code>true</code> if the <code>Timer</code> coalesces
	* multiple pending action events.
	*
	* @see #setCoalesce
	*/
	public boolean isCoalesce() {
	return coalesce;
	}


	/**
	* Sets the string that will be delivered as the action command
	* in <code>ActionEvent</code>s fired by this timer.
	* <code>null</code> is an acceptable value.
	*
	* @param command the action command
	* @since 1.6
	*/
	public void setActionCommand(String command) {
	this.actionCommand = command;
	}


	/**
	* Returns the string that will be delivered as the action command
	* in <code>ActionEvent</code>s fired by this timer. May be
	* <code>null</code>, which is also the default.
	*
	* @return the action command used in firing events
	* @since 1.6
	*/
	public String getActionCommand() {
	return actionCommand;
	}


	/**
	* Starts the <code>Timer</code>,
	* causing it to start sending action events
	* to its listeners.
	*
	* @see #stop
	*/
	public void start() {
	timerQueue().addTimer(this, getInitialDelay());
	}


	/**
	* Returns <code>true</code> if the <code>Timer</code> is running.
	*
	* @see #start
	*/
	public boolean isRunning() {
	return timerQueue().containsTimer(this);
	}


	/**
	* Stops the <code>Timer</code>,
	* causing it to stop sending action events
	* to its listeners.
	*
	* @see #start
	*/
	public void stop() {
	getLock().lock();
	try {
	cancelEvent();
	timerQueue().removeTimer(this);
	} finally {
	getLock().unlock();
	}
	}


	/**
	* Restarts the <code>Timer</code>,
	* canceling any pending firings and causing
	* it to fire with its initial delay.
	*/
	public void restart() {
	getLock().lock();
	try {
	stop();
	start();
	} finally {
	getLock().unlock();
	}
	}


	/**
	* Resets the internal state to indicate this Timer shouldn't notify
	* any of its listeners. This does not stop a repeatable Timer from
	* firing again, use <code>stop</code> for that.
	*/
	void cancelEvent() {
	notify.set(false);
	}


	void post() {
	if (notify.compareAndSet(false, true) \|\| !coalesce) {
	AccessController.doPrivileged(new PrivilegedAction<Void>() {
	public Void run() {
	SwingUtilities.invokeLater(doPostEvent);
	return null;
	}
	}, getAccessControlContext());
	}
	}

	Lock getLock() {
	return lock;
	}

	private void readObject(ObjectInputStream in)
	throws ClassNotFoundException, IOException
	{
	this.acc = AccessController.getContext();
	in.defaultReadObject();
	}

	/*
	* We have to use readResolve because we can not initialize final
	* fields for deserialized object otherwise
	*/
	private Object readResolve() {
	Timer timer = new Timer(getDelay(), null);
	timer.listenerList = listenerList;
	timer.initialDelay = initialDelay;
	timer.delay = delay;
	timer.repeats = repeats;
	timer.coalesce = coalesce;
	timer.actionCommand = actionCommand;
	return timer;
	}
	}

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