Module javafx.graphics

Package javafx.application

Class Platform

java.lang.Object

javafx.application.Platform

public final class Platform
extends Object

Application platform support class.

Since:

JavaFX 2.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	Platform.Preferences	Contains UI preferences of the current platform.

Property Summary

Properties

Type	Property	Description
static ReadOnlyBooleanProperty	accessibilityActive	Indicates whether or not accessibility is active.

Method Summary

Modifier and Type	Method	Description
static ReadOnlyBooleanProperty	accessibilityActiveProperty()	Indicates whether or not accessibility is active.
static boolean	canStartNestedEventLoop()	Indicates whether a nested event loop can be started from the current thread in the current state.
static Object	enterNestedEventLoop(Object key)	Enter a nested event loop and block until the corresponding exitNestedEventLoop call is made.
static void	exit()	Causes the JavaFX application to terminate.
static void	exitNestedEventLoop(Object key, Object rval)	Exit a nested event loop and unblock the caller of the corresponding enterNestedEventLoop.
static Platform.Preferences	getPreferences()	Gets the preferences of the current platform.
static boolean	isAccessibilityActive()	Gets the value of the accessibilityActive property.
static boolean	isFxApplicationThread()	Returns true if the calling thread is the JavaFX Application Thread.
static boolean	isImplicitExit()	Gets the value of the implicitExit attribute.
static Optional<Boolean>	isKeyLocked(KeyCode keyCode)	Returns a flag indicating whether the key corresponding to keyCode is in the locked (or "on") state.
static boolean	isNestedLoopRunning()	Checks whether a nested event loop is running, returning true to indicate that one is, and false if there are no nested event loops currently running.
static boolean	isSupported(ConditionalFeature feature)	Queries whether a specific conditional feature is supported by the platform.
static void	requestNextPulse()	Requests the Java Runtime to perform a pulse.
static void	runLater(Runnable runnable)	Run the specified Runnable on the JavaFX Application Thread at some unspecified time in the future.
static void	setImplicitExit(boolean implicitExit)	Sets the implicitExit attribute to the specified value.
static void	startup(Runnable runnable)	This method starts the JavaFX runtime.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Property Details

accessibilityActive

public static ReadOnlyBooleanProperty accessibilityActiveProperty

Indicates whether or not accessibility is active. This property is typically set to true the first time an assistive technology, such as a screen reader, requests information about any JavaFX window or its children.

This method may be called from any thread.

Since:

JavaFX 8u40

See Also:

• isAccessibilityActive()
• accessibilityActiveProperty()

Method Details

startup

public static void startup(Runnable runnable)

This method starts the JavaFX runtime. The specified Runnable will then be called on the JavaFX Application Thread. In general it is not necessary to explicitly call this method, since it is invoked as a consequence of how most JavaFX applications are built. However there are valid use cases for calling this method directly. Because this method starts the JavaFX runtime, there is not yet any JavaFX Application Thread, so it is normal that this method is called directly on the main thread of the application.

This method may or may not return to the caller before the run method of the specified Runnable has been called. In any case, this method is not blocked on the specified Runnable being executed. Once this method returns, you may call runLater(Runnable) with additional Runnables. Those Runnables will be called, also on the JavaFX Application Thread, after the Runnable passed into this method has been called.

As noted, it is normally the case that the JavaFX Application Thread is started automatically. It is important that this method only be called when the JavaFX runtime has not yet been initialized. Situations where the JavaFX runtime is started automatically include:

• For standard JavaFX applications that extend Application, and use either the Java launcher or one of the launch methods in the Application class to launch the application, the FX runtime is initialized automatically by the launcher before the Application class is loaded.
• For Swing applications that use JFXPanel to display FX content, the FX runtime is initialized when the first JFXPanel instance is constructed.
• For SWT application that use FXCanvas to display FX content, the FX runtime is initialized when the first FXCanvas instance is constructed.

When an application does not follow any of these common approaches, then it becomes the responsibility of the developer to manually start the JavaFX runtime by calling this startup method.

Calling this method when the JavaFX runtime is already running will result in an IllegalStateException being thrown - it is only valid to request that the JavaFX runtime be started once.

Note: The JavaFX classes must be loaded from a set of named javafx.* modules on the module path. Loading the JavaFX classes from the classpath is not supported. A warning is logged when the JavaFX runtime is started if the JavaFX classes are not loaded from the expected named module. This warning is logged regardless of whether the JavaFX runtime was started by calling this method or automatically as described above.

Parameters:

runnable - the Runnable whose run method will be executed on the JavaFX Application Thread once it has been started

Throws:

IllegalStateException - if the JavaFX runtime is already running

Since:

9

See Also:

• Application

runLater

public static void runLater(Runnable runnable)

Run the specified Runnable on the JavaFX Application Thread at some unspecified time in the future. This method, which may be called from any thread, will post the Runnable to an event queue and then return immediately to the caller. The Runnables are executed in the order they are posted. A runnable passed into the runLater method will be executed before any Runnable passed into a subsequent call to runLater. If this method is called after the JavaFX runtime has been shutdown, the call will be ignored: the Runnable will not be executed and no exception will be thrown.

NOTE: applications should avoid flooding JavaFX with too many pending Runnables. Otherwise, the application may become unresponsive. Applications are encouraged to batch up multiple operations into fewer runLater calls. Additionally, long-running operations should be done on a background thread where possible, freeing up the JavaFX Application Thread for GUI operations.

This method must not be called before the FX runtime has been initialized. For standard JavaFX applications that extend Application, and use either the Java launcher or one of the launch methods in the Application class to launch the application, the FX runtime is initialized by the launcher before the Application class is loaded. For Swing applications that use JFXPanel to display FX content, the FX runtime is initialized when the first JFXPanel instance is constructed. For SWT application that use FXCanvas to display FX content, the FX runtime is initialized when the first FXCanvas instance is constructed. For applications that do not follow any of these approaches, then it is necessary to manually start the JavaFX runtime by calling startup(Runnable) once.

Memory consistency effects: Actions in a thread prior to submitting a runnable to this method happen-before actions performed by the runnable in the JavaFX Application Thread.

Parameters:

runnable - the Runnable whose run method will be executed on the JavaFX Application Thread

Throws:

IllegalStateException - if the FX runtime has not been initialized

See Also:

• Application

requestNextPulse

public static void requestNextPulse()

Requests the Java Runtime to perform a pulse. This will run a pulse even if there are no animation timers, scene graph modifications, or window events that would otherwise cause the pulse to run. If no pulse is in progress, then one will be scheduled to run the next time the pulse timer fires. If there is already a pulse running, then at least one more pulse after the current pulse will be scheduled. This method may be called on any thread.

Since:

9

isFxApplicationThread

public static boolean isFxApplicationThread()

Returns true if the calling thread is the JavaFX Application Thread. Use this call to ensure that a given task is being executed (or not being executed) on the JavaFX Application Thread.

Returns:

true if running on the JavaFX Application Thread

exit

public static void exit()

Causes the JavaFX application to terminate. If this method is called after the Application start method is called, then the JavaFX launcher will call the Application stop method and terminate the JavaFX application thread. The launcher thread will then shutdown. If there are no other non-daemon threads that are running, the Java VM will exit. If this method is called from the Preloader or the Application init method, then the Application stop method may not be called.

This method may be called from any thread.

setImplicitExit

public static void setImplicitExit(boolean implicitExit)

Sets the implicitExit attribute to the specified value. If this attribute is true, the JavaFX runtime will implicitly shutdown when the last window is closed; the JavaFX launcher will call the Application.stop() method and terminate the JavaFX application thread. If this attribute is false, the application will continue to run normally even after the last window is closed, until the application calls exit(). The default value is true.

This method may be called from any thread.

Parameters:

implicitExit - a flag indicating whether or not to implicitly exit when the last window is closed.

Since:

JavaFX 2.2

isImplicitExit

public static boolean isImplicitExit()

Gets the value of the implicitExit attribute.

This method may be called from any thread.

Returns:

the implicitExit attribute

Since:

JavaFX 2.2

isSupported

public static boolean isSupported(ConditionalFeature feature)

Queries whether a specific conditional feature is supported by the platform.

For example:

 // Query whether filter effects are supported
 if (Platform.isSupported(ConditionalFeature.EFFECT)) {
    // use effects
 }
 

Parameters:

feature - the conditional feature in question.

Returns:

true if a specific conditional feature is supported by the platform, otherwise false

enterNestedEventLoop

public static Object enterNestedEventLoop(Object key)

Enter a nested event loop and block until the corresponding exitNestedEventLoop call is made. The key passed into this method is used to uniquely identify the matched enter/exit pair. This method creates a new nested event loop and blocks until the corresponding exitNestedEventLoop method is called with the same key. The return value of this method will be the rval object supplied to the exitNestedEventLoop method call that unblocks it.

This method must either be called from an input event handler or from the run method of a Runnable passed to Platform.runLater. It must not be called during animation or layout processing.

Parameters:

key - the Object that identifies the nested event loop, which must not be null

Returns:

the value passed into the corresponding call to exitEventLoop

Throws:

IllegalArgumentException - if the specified key is associated with a nested event loop that has not yet returned

NullPointerException - if the key is null

IllegalStateException - if this method is called during animation or layout processing.

IllegalStateException - if this method is called on a thread other than the JavaFX Application Thread.

Since:

9

exitNestedEventLoop

public static void exitNestedEventLoop(Object key,
 Object rval)

Exit a nested event loop and unblock the caller of the corresponding enterNestedEventLoop. The key passed into this method is used to uniquely identify the matched enter/exit pair. This method causes the nested event loop that was previously created with the key to exit and return control to the caller. If the specified nested event loop is not the inner-most loop then it will not return until all other inner loops also exit.

Parameters:

key - the Object that identifies the nested event loop, which must not be null

rval - an Object that is returned to the caller of the corresponding enterNestedEventLoop. This may be null.

Throws:

IllegalArgumentException - if the specified key is not associated with an active nested event loop

NullPointerException - if the key is null

IllegalStateException - if this method is called on a thread other than the FX Application thread

Since:

9

isKeyLocked

public static Optional<Boolean> isKeyLocked(KeyCode keyCode)

Returns a flag indicating whether the key corresponding to keyCode is in the locked (or "on") state. keyCode must be one of: KeyCode.CAPS or KeyCode.NUM_LOCK. If the underlying system is not able to determine the state of the specified keyCode, an empty Optional is returned. If the keyboard attached to the system doesn't have the specified key, an Optional containing false is returned. This method must be called on the JavaFX Application thread.

Parameters:

keyCode - the KeyCode of the lock state to query

Returns:

the lock state of the key corresponding to keyCode, or an empty Optional if the system cannot determine its state

Throws:

IllegalArgumentException - if keyCode is not one of the valid KeyCode values

IllegalStateException - if this method is called on a thread other than the JavaFX Application Thread

Since:

17

isNestedLoopRunning

public static boolean isNestedLoopRunning()

Checks whether a nested event loop is running, returning true to indicate that one is, and false if there are no nested event loops currently running. This method must be called on the JavaFX Application thread.

Returns:

true if there is a nested event loop running, and false otherwise.

Throws:

IllegalStateException - if this method is called on a thread other than the JavaFX Application Thread.

Since:

9

canStartNestedEventLoop

public static boolean canStartNestedEventLoop()

Indicates whether a nested event loop can be started from the current thread in the current state. A nested event loop can be started from an event handler or from a Runnable passed to runLater(Runnable). This method must be called on the JavaFX Application thread.

Returns:

true if a nested event loop can be started, and false otherwise.

Throws:

IllegalStateException - if this method is called on a thread other than the JavaFX Application Thread.

Since:

21

isAccessibilityActive

public static boolean isAccessibilityActive()

Gets the value of the accessibilityActive property.

Property description:

Indicates whether or not accessibility is active. This property is typically set to true the first time an assistive technology, such as a screen reader, requests information about any JavaFX window or its children.

This method may be called from any thread.

Returns:

the value of the accessibilityActive property

Since:

JavaFX 8u40

See Also:

• accessibilityActiveProperty()

accessibilityActiveProperty

public static ReadOnlyBooleanProperty accessibilityActiveProperty()

Indicates whether or not accessibility is active. This property is typically set to true the first time an assistive technology, such as a screen reader, requests information about any JavaFX window or its children.

This method may be called from any thread.

Returns:

the read-only boolean property indicating if accessibility is active

Since:

JavaFX 8u40

See Also:

• isAccessibilityActive()

getPreferences

public static Platform.Preferences getPreferences()

Gets the preferences of the current platform.

The map returned from this method is unmodifiable, which means that keys and values cannot be added, removed, or updated. Calling any mutator method on the map will always cause UnsupportedOperationException to be thrown. However, the mappings will be updated by JavaFX when the operating system reports that a platform preference has changed.

Returns:

the Preferences instance

Since:

22

See Also:

• Windows preferences
• macOS preferences
• Linux preferences