- java.lang.Object
-
- javax.swing.Timer
-
- All Implemented Interfaces:
Serializable
public class Timer extends Object implements Serializable
Fires one or moreActionEvents at specified intervals. An example use is an animation object that uses aTimeras the trigger for drawing its frames.Setting up a timer involves creating a
Timerobject, registering one or more action listeners on it, and starting the timer using thestartmethod. 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 theTimerconstructor). The second argument to theTimerconstructor specifies a listener to receive the timer's action events.int delay = 1000; //milliseconds ActionListener taskPerformer = new ActionListener() { public void actionPerformed(ActionEvent evt) { //...Perform a task... } }; new Timer(delay, taskPerformer).start();Timersare constructed by specifying both a delay parameter and anActionListener. 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 firstActionEventto registered listeners. After this first event, it continues to fire events every time the between-event delay has elapsed, until it is stopped.After construction, the initial delay and the between-event delay can be changed independently, and additional
ActionListenersmay be added.If you want the timer to fire only the first time and then stop, invoke
setRepeats(false)on the timer.Although all
Timers perform their waiting using a single, shared thread (created by the firstTimerobject that executes), the action event handlers forTimers execute on another thread -- the event-dispatching thread. This means that the action handlers forTimers can safely perform operations on Swing components. However, it also means that the handlers must execute quickly to keep the GUI responsive.In v 1.3, another
Timerclass was added to the Java platform:java.util.Timer. Both it andjavax.swing.Timerprovide the same basic functionality, butjava.util.Timeris more general and has more features. Thejavax.swing.Timerhas 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.You can find further documentation and several examples of using timers by visiting How to Use Timers, a section in The Java Tutorial. For more examples and help in choosing between this
Timerclass andjava.util.Timer, see Using Timers in Swing Applications, an article in The Swing Connection.Warning: 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
java.beanspackage. Please seeXMLEncoder.- Since:
- 1.2
- See Also:
Timer, Serialized Form
-
-
Field Summary
Fields Modifier and Type Field Description protected EventListenerListlistenerListThe collection of registered listeners
-
Constructor Summary
Constructors Constructor Description Timer(int delay, ActionListener listener)Creates aTimerand initializes both the initial delay and between-event delay todelaymilliseconds.
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description voidaddActionListener(ActionListener listener)Adds an action listener to theTimer.protected voidfireActionPerformed(ActionEvent e)Notifies all listeners that have registered interest for notification on this event type.StringgetActionCommand()Returns the string that will be delivered as the action command inActionEvents fired by this timer.ActionListener[]getActionListeners()Returns an array of all the action listeners registered on this timer.intgetDelay()Returns the delay, in milliseconds, between firings of action events.intgetInitialDelay()Returns theTimer's initial delay.<T extends EventListener>
T[]getListeners(Class<T> listenerType)Returns an array of all the objects currently registered asFooListeners upon thisTimer.static booleangetLogTimers()Returnstrueif logging is enabled.booleanisCoalesce()Returnstrueif theTimercoalesces multiple pending action events.booleanisRepeats()Returnstrue(the default) if theTimerwill send an action event to its listeners multiple times.booleanisRunning()Returnstrueif theTimeris running.voidremoveActionListener(ActionListener listener)Removes the specified action listener from theTimer.voidrestart()Restarts theTimer, canceling any pending firings and causing it to fire with its initial delay.voidsetActionCommand(String command)Sets the string that will be delivered as the action command inActionEvents fired by this timer.voidsetCoalesce(boolean flag)Sets whether theTimercoalesces multiple pendingActionEventfirings.voidsetDelay(int delay)Sets theTimer's between-event delay, the number of milliseconds between successive action events.voidsetInitialDelay(int initialDelay)Sets theTimer's initial delay, the time in milliseconds to wait after the timer is started before firing the first event.static voidsetLogTimers(boolean flag)Enables or disables the timer log.voidsetRepeats(boolean flag)Ifflagisfalse, instructs theTimerto send only one action event to its listeners.voidstart()Starts theTimer, causing it to start sending action events to its listeners.voidstop()Stops theTimer, causing it to stop sending action events to its listeners.
-
-
-
Field Detail
-
listenerList
protected EventListenerList listenerList
The collection of registered listeners
-
-
Constructor Detail
-
Timer
public Timer(int delay, ActionListener listener)Creates aTimerand initializes both the initial delay and between-event delay todelaymilliseconds. Ifdelayis less than or equal to zero, the timer fires as soon as it is started. Iflisteneris notnull, it's registered as an action listener on the timer.- Parameters:
delay- milliseconds for the initial and between-event delaylistener- an initial listener; can benull- See Also:
addActionListener(java.awt.event.ActionListener),setInitialDelay(int),setRepeats(boolean)
-
-
Method Detail
-
addActionListener
public void addActionListener(ActionListener listener)
Adds an action listener to theTimer.- Parameters:
listener- the listener to add- See Also:
Timer(int, java.awt.event.ActionListener)
-
removeActionListener
public void removeActionListener(ActionListener listener)
Removes the specified action listener from theTimer.- Parameters:
listener- the listener to remove
-
getActionListeners
public ActionListener[] getActionListeners()
Returns an array of all the action listeners registered on this timer.- Returns:
- all of the timer's
ActionListeners or an empty array if no action listeners are currently registered - Since:
- 1.4
- See Also:
addActionListener(java.awt.event.ActionListener),removeActionListener(java.awt.event.ActionListener)
-
fireActionPerformed
protected void fireActionPerformed(ActionEvent e)
Notifies all listeners that have registered interest for notification on this event type.- Parameters:
e- the action event to fire- See Also:
EventListenerList
-
getListeners
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered asFooListeners upon thisTimer.FooListeners are registered using theaddFooListenermethod.You can specify the
listenerTypeargument with a class literal, such asFooListener.class. For example, you can query aTimerinstancetfor its action listeners with the following code:ActionListener[] als = (ActionListener[])(t.getListeners(ActionListener.class));
If no such listeners exist, this method returns an empty array.- Type Parameters:
T- the type ofEventListenerclass being requested- Parameters:
listenerType- the type of listeners requested; this parameter should specify an interface that descends fromjava.util.EventListener- Returns:
- an array of all objects registered as
FooListeners on this timer, or an empty array if no such listeners have been added - Throws:
ClassCastException- iflistenerTypedoesn't specify a class or interface that implementsjava.util.EventListener- Since:
- 1.3
- See Also:
getActionListeners(),addActionListener(java.awt.event.ActionListener),removeActionListener(java.awt.event.ActionListener)
-
setLogTimers
public static void setLogTimers(boolean flag)
Enables or disables the timer log. When enabled, a message is posted toSystem.outwhenever the timer goes off.- Parameters:
flag-trueto enable logging- See Also:
getLogTimers()
-
getLogTimers
public static boolean getLogTimers()
Returnstrueif logging is enabled.- Returns:
trueif logging is enabled; otherwise, false- See Also:
setLogTimers(boolean)
-
setDelay
public void setDelay(int delay)
Sets theTimer'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 thesetInitialDelaymethod.- Parameters:
delay- the delay in milliseconds- See Also:
setInitialDelay(int)
-
getDelay
public int getDelay()
Returns the delay, in milliseconds, between firings of action events.- Returns:
- the delay, in milliseconds, between firings of action events
- See Also:
setDelay(int),getInitialDelay()
-
setInitialDelay
public void setInitialDelay(int initialDelay)
Sets theTimer'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.- Parameters:
initialDelay- the initial delay, in milliseconds- See Also:
setDelay(int)
-
getInitialDelay
public int getInitialDelay()
Returns theTimer's initial delay.- Returns:
- the
Timer's intial delay, in milliseconds - See Also:
setInitialDelay(int),setDelay(int)
-
setRepeats
public void setRepeats(boolean flag)
Ifflagisfalse, instructs theTimerto send only one action event to its listeners.- Parameters:
flag- specifyfalseto make the timer stop after sending its first action event
-
isRepeats
public boolean isRepeats()
Returnstrue(the default) if theTimerwill send an action event to its listeners multiple times.- Returns:
- true if the
Timerwill send an action event to its listeners multiple times - See Also:
setRepeats(boolean)
-
setCoalesce
public void setCoalesce(boolean flag)
Sets whether theTimercoalesces multiple pendingActionEventfirings. A busy application may not be able to keep up with aTimer's event generation, causing multiple action events to be queued. When processed, the application sends these events one after the other, causing theTimer'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.Timers coalesce events by default.- Parameters:
flag- specifyfalseto turn off coalescing
-
isCoalesce
public boolean isCoalesce()
Returnstrueif theTimercoalesces multiple pending action events.- Returns:
- true if the
Timercoalesces multiple pending action events - See Also:
setCoalesce(boolean)
-
setActionCommand
public void setActionCommand(String command)
Sets the string that will be delivered as the action command inActionEvents fired by this timer.nullis an acceptable value.- Parameters:
command- the action command- Since:
- 1.6
-
getActionCommand
public String getActionCommand()
Returns the string that will be delivered as the action command inActionEvents fired by this timer. May benull, which is also the default.- Returns:
- the action command used in firing events
- Since:
- 1.6
-
start
public void start()
Starts theTimer, causing it to start sending action events to its listeners.- See Also:
stop()
-
isRunning
public boolean isRunning()
Returnstrueif theTimeris running.- Returns:
- true if the
Timeris running, false otherwise - See Also:
start()
-
stop
public void stop()
Stops theTimer, causing it to stop sending action events to its listeners.- See Also:
start()
-
restart
public void restart()
Restarts theTimer, canceling any pending firings and causing it to fire with its initial delay.
-
-