- Type Parameters:
V
- the type of object returned by the Service
- All Implemented Interfaces:
Worker<V>
,EventTarget
- Direct Known Subclasses:
ScheduledService
public abstract class Service<V> extends Object implements Worker<V>, EventTarget
A Service is a non-visual component encapsulating the information required to perform some work on one or more background threads. As part of the JavaFX UI library, the Service knows about the JavaFX Application thread and is designed to relieve the application developer from the burden of managing multithreaded code that interacts with the user interface. As such, all of the methods and state on the Service are intended to be invoked exclusively from the JavaFX Application thread. The only exception to this, is when initially configuring a Service, which may safely be done from any thread, and initially starting a Service, which may also safely be done from any thread. However, once the Service has been initialized and started, it may only thereafter be used from the FX thread.
A Service creates and manages a Task
that performs the work
on the background thread.
Service implements Worker
. As such, you can observe the state of
the background task and optionally cancel it. Service is a reusable
Worker, meaning that it can be reset and restarted. Due to this, a Service
can be constructed declaratively and restarted on demand.
Once a Service is started, it will schedule its Task and listen for
changes to the state of the Task. A Task does not hold a reference to the
Service that started it, meaning that a running Task will not prevent
the Service from being garbage collected.
If an Executor
is specified on the Service,
then it will be used to actually execute the service. Otherwise,
a daemon thread will be created and executed. If you wish to create
non-daemon threads, then specify a custom Executor (for example,
you could use a ThreadPoolExecutor
with a custom
ThreadFactory
).
Because a Service is intended to simplify declarative use cases, subclasses
should expose as properties the input parameters to the work to be done.
For example, suppose I wanted to write a Service which read the first line
from any URL and returned it as a String. Such a Service might be defined,
such that it had a single property, url
. It might be implemented
as:
public static class FirstLineService extends Service<String> {
private StringProperty url = new SimpleStringProperty(this, "url");
public final void setUrl(String value) { url.set(value); }
public final String getUrl() { return url.get(); }
public final StringProperty urlProperty() { return url; }
protected Task createTask() {
final String _url = getUrl();
return new Task<String>() {
protected String call() throws Exception {
URL u = new URL(_url);
BufferedReader in = new BufferedReader(
new InputStreamReader(u.openStream()));
String result = in.readLine();
in.close();
return result;
}
};
}
}
The Service by default uses a thread pool Executor with some unspecified default or maximum thread pool size. This is done so that naive code will not completely swamp the system by creating thousands of Threads.
- Since:
- JavaFX 2.0
-
Property Summary
Properties Type Property Description ReadOnlyObjectProperty<Throwable>
exception
Gets the ReadOnlyObjectProperty representing any exception which occurred.ObjectProperty<Executor>
executor
The executor to use for running this Service.ReadOnlyStringProperty
message
Gets the ReadOnlyStringProperty representing the message.ObjectProperty<EventHandler<WorkerStateEvent>>
onCancelled
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onFailed
The onFailed event handler is called whenever the Task state transitions to the FAILED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onReady
The onReady event handler is called whenever the Task state transitions to the READY state.ObjectProperty<EventHandler<WorkerStateEvent>>
onRunning
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.ObjectProperty<EventHandler<WorkerStateEvent>>
onScheduled
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onSucceeded
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.ReadOnlyDoubleProperty
progress
Gets the ReadOnlyDoubleProperty representing the progress.ReadOnlyBooleanProperty
running
Gets the ReadOnlyBooleanProperty representing whether the Worker is running.ReadOnlyObjectProperty<Worker.State>
state
Gets the ReadOnlyObjectProperty representing the current state.ReadOnlyStringProperty
title
Gets the ReadOnlyStringProperty representing the title.ReadOnlyDoubleProperty
totalWork
Gets the ReadOnlyDoubleProperty representing the maximum amount of work that needs to be done.ReadOnlyObjectProperty<V>
value
Gets the ReadOnlyObjectProperty representing the value.ReadOnlyDoubleProperty
workDone
Gets the ReadOnlyDoubleProperty representing the current progress. -
Nested Class Summary
Nested classes/interfaces inherited from interface javafx.concurrent.Worker
Worker.State
-
Constructor Summary
Constructors Modifier Constructor Description protected
Service()
Create a new Service. -
Method Summary
Modifier and Type Method Description <T extends Event>
voidaddEventFilter(EventType<T> eventType, EventHandler<? super T> eventFilter)
Registers an event filter to this task.<T extends Event>
voidaddEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)
Registers an event handler to this task.EventDispatchChain
buildEventDispatchChain(EventDispatchChain tail)
Construct an event dispatch chain for this target.boolean
cancel()
Cancels any currently running Task, if any.protected void
cancelled()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the CANCELLED state.protected abstract Task<V>
createTask()
Invoked after the Service is started on the JavaFX Application Thread.ReadOnlyObjectProperty<Throwable>
exceptionProperty()
Gets the ReadOnlyObjectProperty representing any exception which occurred.protected void
executeTask(Task<V> task)
Uses theexecutor
defined on this Service to execute the given task.ObjectProperty<Executor>
executorProperty()
The executor to use for running this Service.protected void
failed()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the FAILED state.protected void
fireEvent(Event event)
Fires the specified event.Throwable
getException()
Gets the value of the property exception.Executor
getExecutor()
Gets the value of the property executor.String
getMessage()
Gets the value of the property message.EventHandler<WorkerStateEvent>
getOnCancelled()
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.EventHandler<WorkerStateEvent>
getOnFailed()
The onFailed event handler is called whenever the Task state transitions to the FAILED state.EventHandler<WorkerStateEvent>
getOnReady()
The onReady event handler is called whenever the Task state transitions to the READY state.EventHandler<WorkerStateEvent>
getOnRunning()
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.EventHandler<WorkerStateEvent>
getOnScheduled()
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.EventHandler<WorkerStateEvent>
getOnSucceeded()
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.double
getProgress()
Gets the value of the property progress.Worker.State
getState()
Gets the value of the property state.String
getTitle()
Gets the value of the property title.double
getTotalWork()
Gets the value of the property totalWork.V
getValue()
Gets the value of the property value.double
getWorkDone()
Gets the value of the property workDone.boolean
isRunning()
Gets the value of the property running.ReadOnlyStringProperty
messageProperty()
Gets the ReadOnlyStringProperty representing the message.ObjectProperty<EventHandler<WorkerStateEvent>>
onCancelledProperty()
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onFailedProperty()
The onFailed event handler is called whenever the Task state transitions to the FAILED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onReadyProperty()
The onReady event handler is called whenever the Task state transitions to the READY state.ObjectProperty<EventHandler<WorkerStateEvent>>
onRunningProperty()
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.ObjectProperty<EventHandler<WorkerStateEvent>>
onScheduledProperty()
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.ObjectProperty<EventHandler<WorkerStateEvent>>
onSucceededProperty()
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.ReadOnlyDoubleProperty
progressProperty()
Gets the ReadOnlyDoubleProperty representing the progress.protected void
ready()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the READY state.<T extends Event>
voidremoveEventFilter(EventType<T> eventType, EventHandler<? super T> eventFilter)
Unregisters a previously registered event filter from this task.<T extends Event>
voidremoveEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)
Unregisters a previously registered event handler from this task.void
reset()
Resets the Service.void
restart()
Cancels any currently running Task, if any, and restarts this Service.protected void
running()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the RUNNING state.ReadOnlyBooleanProperty
runningProperty()
Gets the ReadOnlyBooleanProperty representing whether the Worker is running.protected void
scheduled()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the SCHEDULED state.protected <T extends Event>
voidsetEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)
Sets the handler to use for this event type.void
setExecutor(Executor value)
Sets the value of the property executor.void
setOnCancelled(EventHandler<WorkerStateEvent> value)
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.void
setOnFailed(EventHandler<WorkerStateEvent> value)
The onFailed event handler is called whenever the Task state transitions to the FAILED state.void
setOnReady(EventHandler<WorkerStateEvent> value)
The onReady event handler is called whenever the Task state transitions to the READY state.void
setOnRunning(EventHandler<WorkerStateEvent> value)
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.void
setOnScheduled(EventHandler<WorkerStateEvent> value)
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.void
setOnSucceeded(EventHandler<WorkerStateEvent> value)
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.void
start()
Starts this Service.ReadOnlyObjectProperty<Worker.State>
stateProperty()
Gets the ReadOnlyObjectProperty representing the current state.protected void
succeeded()
A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the SUCCEEDED state.ReadOnlyStringProperty
titleProperty()
Gets the ReadOnlyStringProperty representing the title.ReadOnlyDoubleProperty
totalWorkProperty()
Gets the ReadOnlyDoubleProperty representing the maximum amount of work that needs to be done.ReadOnlyObjectProperty<V>
valueProperty()
Gets the ReadOnlyObjectProperty representing the value.ReadOnlyDoubleProperty
workDoneProperty()
Gets the ReadOnlyDoubleProperty representing the current progress.
-
Property Details
-
state
- Specified by:
stateProperty
in interfaceWorker<V>
- See Also:
getState()
-
value
- Specified by:
valueProperty
in interfaceWorker<V>
- See Also:
getValue()
-
exception
- Specified by:
exceptionProperty
in interfaceWorker<V>
- See Also:
getException()
-
workDone
- Specified by:
workDoneProperty
in interfaceWorker<V>
- See Also:
getWorkDone()
-
totalWork
- Specified by:
totalWorkProperty
in interfaceWorker<V>
- See Also:
getTotalWork()
-
progress
- Specified by:
progressProperty
in interfaceWorker<V>
- See Also:
getProgress()
-
running
- Specified by:
runningProperty
in interfaceWorker<V>
- See Also:
isRunning()
-
message
- Specified by:
messageProperty
in interfaceWorker<V>
- See Also:
getMessage()
-
title
- Specified by:
titleProperty
in interfaceWorker<V>
- See Also:
getTitle()
-
executor
The executor to use for running this Service. If no executor is specified, then a new daemon thread will be created and used for running the Service using some default executor.- See Also:
getExecutor()
,setExecutor(Executor)
-
onReady
The onReady event handler is called whenever the Task state transitions to the READY state.- Since:
- JavaFX 2.1
- See Also:
getOnReady()
,setOnReady(EventHandler)
-
onScheduled
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.- Since:
- JavaFX 2.1
- See Also:
getOnScheduled()
,setOnScheduled(EventHandler)
-
onRunning
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.- Since:
- JavaFX 2.1
- See Also:
getOnRunning()
,setOnRunning(EventHandler)
-
onSucceeded
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.- Since:
- JavaFX 2.1
- See Also:
getOnSucceeded()
,setOnSucceeded(EventHandler)
-
onCancelled
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.- Since:
- JavaFX 2.1
- See Also:
getOnCancelled()
,setOnCancelled(EventHandler)
-
onFailed
The onFailed event handler is called whenever the Task state transitions to the FAILED state.- Since:
- JavaFX 2.1
- See Also:
getOnFailed()
,setOnFailed(EventHandler)
-
-
Constructor Details
-
Service
protected Service()Create a new Service.
-
-
Method Details
-
getState
Gets the value of the property state. -
stateProperty
Description copied from interface:Worker
Gets the ReadOnlyObjectProperty representing the current state.- Specified by:
stateProperty
in interfaceWorker<V>
- See Also:
getState()
-
getValue
Gets the value of the property value. -
valueProperty
Description copied from interface:Worker
Gets the ReadOnlyObjectProperty representing the value.- Specified by:
valueProperty
in interfaceWorker<V>
- See Also:
getValue()
-
getException
Gets the value of the property exception.- Specified by:
getException
in interfaceWorker<V>
- Property description:
- Returns:
- the exception, if one occurred
-
exceptionProperty
Description copied from interface:Worker
Gets the ReadOnlyObjectProperty representing any exception which occurred.- Specified by:
exceptionProperty
in interfaceWorker<V>
- See Also:
getException()
-
getWorkDone
public final double getWorkDone()Gets the value of the property workDone.- Specified by:
getWorkDone
in interfaceWorker<V>
- Property description:
- Returns:
- the amount of work done
- See Also:
Worker.totalWorkProperty()
,Worker.progressProperty()
-
workDoneProperty
Description copied from interface:Worker
Gets the ReadOnlyDoubleProperty representing the current progress.- Specified by:
workDoneProperty
in interfaceWorker<V>
- See Also:
getWorkDone()
-
getTotalWork
public final double getTotalWork()Gets the value of the property totalWork.- Specified by:
getTotalWork
in interfaceWorker<V>
- Property description:
- Returns:
- the total work to be done
- See Also:
Worker.workDoneProperty()
,Worker.progressProperty()
-
totalWorkProperty
Description copied from interface:Worker
Gets the ReadOnlyDoubleProperty representing the maximum amount of work that needs to be done. These "work units" have meaning to the Worker implementation, such as the number of bytes that need to be downloaded or the number of images to process or some other such metric.- Specified by:
totalWorkProperty
in interfaceWorker<V>
- See Also:
getTotalWork()
-
getProgress
public final double getProgress()Gets the value of the property progress.- Specified by:
getProgress
in interfaceWorker<V>
- Property description:
- Returns:
- the current progress
- See Also:
Worker.workDoneProperty()
,Worker.totalWorkProperty()
-
progressProperty
Description copied from interface:Worker
Gets the ReadOnlyDoubleProperty representing the progress.- Specified by:
progressProperty
in interfaceWorker<V>
- See Also:
getProgress()
-
isRunning
public final boolean isRunning()Gets the value of the property running. -
runningProperty
Description copied from interface:Worker
Gets the ReadOnlyBooleanProperty representing whether the Worker is running.- Specified by:
runningProperty
in interfaceWorker<V>
- See Also:
isRunning()
-
getMessage
Gets the value of the property message.- Specified by:
getMessage
in interfaceWorker<V>
- Property description:
- Returns:
- the current message
-
messageProperty
Description copied from interface:Worker
Gets the ReadOnlyStringProperty representing the message.- Specified by:
messageProperty
in interfaceWorker<V>
- See Also:
getMessage()
-
getTitle
Gets the value of the property title. -
titleProperty
Description copied from interface:Worker
Gets the ReadOnlyStringProperty representing the title.- Specified by:
titleProperty
in interfaceWorker<V>
- See Also:
getTitle()
-
setExecutor
Sets the value of the property executor.- Property description:
- The executor to use for running this Service. If no executor is specified, then a new daemon thread will be created and used for running the Service using some default executor.
-
getExecutor
Gets the value of the property executor.- Property description:
- The executor to use for running this Service. If no executor is specified, then a new daemon thread will be created and used for running the Service using some default executor.
-
executorProperty
The executor to use for running this Service. If no executor is specified, then a new daemon thread will be created and used for running the Service using some default executor.- See Also:
getExecutor()
,setExecutor(Executor)
-
onReadyProperty
The onReady event handler is called whenever the Task state transitions to the READY state.- Since:
- JavaFX 2.1
- See Also:
getOnReady()
,setOnReady(EventHandler)
-
getOnReady
The onReady event handler is called whenever the Task state transitions to the READY state.- Returns:
- the onReady event handler, if any
- Since:
- JavaFX 2.1
-
setOnReady
The onReady event handler is called whenever the Task state transitions to the READY state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
ready
protected void ready()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the READY state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
onScheduledProperty
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.- Since:
- JavaFX 2.1
- See Also:
getOnScheduled()
,setOnScheduled(EventHandler)
-
getOnScheduled
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.- Returns:
- the onScheduled event handler, if any
- Since:
- JavaFX 2.1
-
setOnScheduled
The onSchedule event handler is called whenever the Task state transitions to the SCHEDULED state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
scheduled
protected void scheduled()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the SCHEDULED state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
onRunningProperty
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.- Since:
- JavaFX 2.1
- See Also:
getOnRunning()
,setOnRunning(EventHandler)
-
getOnRunning
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.- Returns:
- the onRunning event handler, if any
- Since:
- JavaFX 2.1
-
setOnRunning
The onRunning event handler is called whenever the Task state transitions to the RUNNING state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
running
protected void running()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the RUNNING state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
onSucceededProperty
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.- Since:
- JavaFX 2.1
- See Also:
getOnSucceeded()
,setOnSucceeded(EventHandler)
-
getOnSucceeded
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.- Returns:
- the onSucceeded event handler, if any
- Since:
- JavaFX 2.1
-
setOnSucceeded
The onSucceeded event handler is called whenever the Task state transitions to the SUCCEEDED state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
succeeded
protected void succeeded()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the SUCCEEDED state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
onCancelledProperty
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.- Since:
- JavaFX 2.1
- See Also:
getOnCancelled()
,setOnCancelled(EventHandler)
-
getOnCancelled
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.- Returns:
- the onCancelled event handler, if any
- Since:
- JavaFX 2.1
-
setOnCancelled
The onCancelled event handler is called whenever the Task state transitions to the CANCELLED state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
cancelled
protected void cancelled()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the CANCELLED state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
onFailedProperty
The onFailed event handler is called whenever the Task state transitions to the FAILED state.- Since:
- JavaFX 2.1
- See Also:
getOnFailed()
,setOnFailed(EventHandler)
-
getOnFailed
The onFailed event handler is called whenever the Task state transitions to the FAILED state.- Returns:
- the onFailed event handler, if any
- Since:
- JavaFX 2.1
-
setOnFailed
The onFailed event handler is called whenever the Task state transitions to the FAILED state.- Parameters:
value
- the event handler, can be null to clear it- Since:
- JavaFX 2.1
-
failed
protected void failed()A protected convenience method for subclasses, called whenever the state of the Service has transitioned to the FAILED state. This method is invoked after the Service has been fully transitioned to the new state.- Since:
- JavaFX 2.1
-
cancel
public boolean cancel()Cancels any currently running Task, if any. The state will be set to CANCELLED. -
restart
public void restart()Cancels any currently running Task, if any, and restarts this Service. The state will be reset to READY prior to execution. This method should only be called on the FX application thread. -
reset
public void reset()Resets the Service. May only be called while in one of the finish states, that is, SUCCEEDED, FAILED, or CANCELLED, or when READY. This method should only be called on the FX application thread. -
start
public void start()Starts this Service. The Service must be in the READY state to succeed in this call. This method should only be called on the FX application thread. -
executeTask
Uses the
executor
defined on this Service to execute the given task. If theexecutor
is null, then a default executor is used which will create a new daemon thread on which to execute this task.This method is intended only to be called by the Service implementation.
- Parameters:
task
- a non-null task to execute- Since:
- JavaFX 2.1
-
addEventHandler
public final <T extends Event> void addEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)Registers an event handler to this task. Any event filters are first processed, then the specified onFoo event handlers, and finally any event handlers registered by this method. As with other events in the scene graph, if an event is consumed, it will not continue dispatching.- Type Parameters:
T
- the specific event class of the handler- Parameters:
eventType
- the type of the events to receive by the handlereventHandler
- the handler to register- Throws:
NullPointerException
- if the event type or handler is null- Since:
- JavaFX 2.1
-
removeEventHandler
public final <T extends Event> void removeEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)Unregisters a previously registered event handler from this task. One handler might have been registered for different event types, so the caller needs to specify the particular event type from which to unregister the handler.- Type Parameters:
T
- the specific event class of the handler- Parameters:
eventType
- the event type from which to unregistereventHandler
- the handler to unregister- Throws:
NullPointerException
- if the event type or handler is null- Since:
- JavaFX 2.1
-
addEventFilter
public final <T extends Event> void addEventFilter(EventType<T> eventType, EventHandler<? super T> eventFilter)Registers an event filter to this task. Registered event filters get an event before any associated event handlers.- Type Parameters:
T
- the specific event class of the filter- Parameters:
eventType
- the type of the events to receive by the filtereventFilter
- the filter to register- Throws:
NullPointerException
- if the event type or filter is null- Since:
- JavaFX 2.1
-
removeEventFilter
public final <T extends Event> void removeEventFilter(EventType<T> eventType, EventHandler<? super T> eventFilter)Unregisters a previously registered event filter from this task. One filter might have been registered for different event types, so the caller needs to specify the particular event type from which to unregister the filter.- Type Parameters:
T
- the specific event class of the filter- Parameters:
eventType
- the event type from which to unregistereventFilter
- the filter to unregister- Throws:
NullPointerException
- if the event type or filter is null- Since:
- JavaFX 2.1
-
setEventHandler
protected final <T extends Event> void setEventHandler(EventType<T> eventType, EventHandler<? super T> eventHandler)Sets the handler to use for this event type. There can only be one such handler specified at a time. This handler is guaranteed to be called first. This is used for registering the user-defined onFoo event handlers.- Type Parameters:
T
- the specific event class of the handler- Parameters:
eventType
- the event type to associate with the given eventHandlereventHandler
- the handler to register, or null to unregister- Throws:
NullPointerException
- if the event type is null- Since:
- JavaFX 2.1
-
fireEvent
Fires the specified event. Any event filter encountered will be notified and can consume the event. If not consumed by the filters, the event handlers on this task are notified. If these don't consume the event either, then all event handlers are called and can consume the event.This method must be called on the FX user thread.
- Parameters:
event
- the event to fire- Since:
- JavaFX 2.1
-
buildEventDispatchChain
Description copied from interface:EventTarget
Construct an event dispatch chain for this target. The event dispatch chain contains event dispatchers which might be interested in processing of events targeted at thisEventTarget
. This event target is not automatically added to the chain, so if it wants to process events, it needs to add anEventDispatcher
for itself to the chain.In the case the event target is part of some hierarchy, the chain for it is usually built from event dispatchers collected from the root of the hierarchy to the event target.
The event dispatch chain is constructed by modifications to the provided initial event dispatch chain. The returned chain should have the initial chain at its end so the dispatchers should be prepended to the initial chain.
The caller shouldn't assume that the initial chain remains unchanged nor that the returned value will reference a different chain.
- Specified by:
buildEventDispatchChain
in interfaceEventTarget
- Parameters:
tail
- the initial chain to build from- Returns:
- the resulting event dispatch chain for this target
-
createTask
Invoked after the Service is started on the JavaFX Application Thread. Implementations should save off any state into final variables prior to creating the Task, since accessing properties defined on the Service within the background thread code of the Task will result in exceptions. For example:protected Task createTask() { final String url = myService.getUrl(); return new Task<String>() { protected String call() { URL u = new URL("http://www.oracle.com"); BufferedReader in = new BufferedReader( new InputStreamReader(u.openStream())); String result = in.readLine(); in.close(); return result; } } }
If the Task is a pre-defined class (as opposed to being an anonymous class), and if it followed the recommended best-practice, then there is no need to save off state prior to constructing the Task since its state is completely provided in its constructor.
protected Task createTask() { // This is safe because getUrl is called on the FX Application // Thread and the FirstLineReaderTasks stores it as an // immutable property return new FirstLineReaderTask(myService.getUrl()); }
- Returns:
- the Task to execute
-