Module java.desktop

Package java.awt.event

Class InvocationEvent

java.lang.Object

java.util.EventObject

java.awt.AWTEvent

java.awt.event.InvocationEvent

All Implemented Interfaces:

ActiveEvent, Serializable

public class InvocationEvent
extends AWTEvent
implements ActiveEvent

An event which executes the run() method on a Runnable when dispatched by the AWT event dispatcher thread. This class can be used as a reference implementation of ActiveEvent rather than declaring a new class and defining dispatch().

Instances of this class are placed on the EventQueue by calls to invokeLater and invokeAndWait. Client code can use this fact to write replacement functions for invokeLater and invokeAndWait without writing special-case code in any AWTEventListener objects.

An unspecified behavior will be caused if the id parameter of any particular InvocationEvent instance is not in the range from INVOCATION_FIRST to INVOCATION_LAST.

Since:

1.2

See Also:

• ActiveEvent
• EventQueue.invokeLater(java.lang.Runnable)
• EventQueue.invokeAndWait(java.lang.Runnable)
• AWTEventListener
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	catchExceptions	Set to true if dispatch() catches Throwable and stores it in the exception instance variable.
static final int	INVOCATION_DEFAULT	The default id for all InvocationEvents.
static final int	INVOCATION_FIRST	Marks the first integer id for the range of invocation event ids.
static final int	INVOCATION_LAST	Marks the last integer id for the range of invocation event ids.
protected Object	notifier	The (potentially null) Object whose notifyAll() method will be called immediately after the Runnable.run() method has returned or thrown an exception or after the event was disposed.
protected Runnable	runnable	The Runnable whose run() method will be called.

Fields declared in class java.awt.AWTEvent

ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK

Fields declared in class java.util.EventObject

source

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	InvocationEvent(Object source, int id, Runnable runnable, Object notifier, boolean catchThrowables)	Constructs an InvocationEvent with the specified source and ID which will execute the runnable's run() method when dispatched.
	InvocationEvent(Object source, Runnable runnable)	Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched.
	InvocationEvent(Object source, Runnable runnable, Object notifier, boolean catchThrowables)	Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched.
	InvocationEvent(Object source, Runnable runnable, Runnable listener, boolean catchThrowables)	Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched.

Method Summary

Modifier and Type	Method	Description
void	dispatch()	Executes the Runnable's run() method and notifies the notifier (if any) when run() has returned or thrown an exception.
Exception	getException()	Returns any Exception caught while executing the Runnable's run() method.
Throwable	getThrowable()	Returns any Throwable caught while executing the Runnable's run() method.
long	getWhen()	Returns the timestamp of when this event occurred.
boolean	isDispatched()	Returns true if the event is dispatched or any exception is thrown while dispatching, false otherwise.
String	paramString()	Returns a parameter string identifying this event.

Methods declared in class java.awt.AWTEvent

consume, getID, isConsumed, setSource, toString

Methods declared in class java.util.EventObject

getSource

Methods declared in class java.lang.Object

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

Field Details

INVOCATION_FIRST

public static final int INVOCATION_FIRST

Marks the first integer id for the range of invocation event ids.

See Also:

• Constant Field Values

INVOCATION_DEFAULT

public static final int INVOCATION_DEFAULT

The default id for all InvocationEvents.

See Also:

• Constant Field Values

INVOCATION_LAST

public static final int INVOCATION_LAST

Marks the last integer id for the range of invocation event ids.

See Also:

• Constant Field Values

runnable

protected Runnable runnable

The Runnable whose run() method will be called.

notifier

protected volatile Object notifier

The (potentially null) Object whose notifyAll() method will be called immediately after the Runnable.run() method has returned or thrown an exception or after the event was disposed.

See Also:

• isDispatched()

catchExceptions

protected boolean catchExceptions

Set to true if dispatch() catches Throwable and stores it in the exception instance variable. If false, Throwables are propagated up to the EventDispatchThread's dispatch loop.

Constructor Details

InvocationEvent

public InvocationEvent(Object source,
 Runnable runnable)

Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched.

This is a convenience constructor. An invocation of the form InvocationEvent(source, runnable) behaves in exactly the same way as the invocation of InvocationEvent(source, runnable, null, false).

This method throws an IllegalArgumentException if source is null.

Parameters:

source - The Object that originated the event

runnable - The Runnable whose run() method will be executed

Throws:

IllegalArgumentException - if source is null

See Also:

• EventObject.getSource()
• InvocationEvent(Object, Runnable, Object, boolean)

InvocationEvent

public InvocationEvent(Object source,
 Runnable runnable,
 Object notifier,
 boolean catchThrowables)

Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched. If notifier is non-null, notifyAll() will be called on it immediately after run() has returned or thrown an exception.

An invocation of the form InvocationEvent(source, runnable, notifier, catchThrowables) behaves in exactly the same way as the invocation of InvocationEvent(source, InvocationEvent.INVOCATION_DEFAULT, runnable, notifier, catchThrowables).

This method throws an IllegalArgumentException if source is null.

Parameters:

source - The Object that originated the event

runnable - The Runnable whose run() method will be executed

notifier - The Object whose notifyAll method will be called after Runnable.run has returned or thrown an exception or after the event was disposed

catchThrowables - Specifies whether dispatch should catch Throwable when executing the Runnable's run() method, or should instead propagate those Throwables to the EventDispatchThread's dispatch loop

Throws:

IllegalArgumentException - if source is null

See Also:

• EventObject.getSource()
• InvocationEvent(Object, int, Runnable, Object, boolean)

InvocationEvent

public InvocationEvent(Object source,
 Runnable runnable,
 Runnable listener,
 boolean catchThrowables)

Constructs an InvocationEvent with the specified source which will execute the runnable's run() method when dispatched. If listener is non-null, listener.run() will be called immediately after run has returned, thrown an exception or the event was disposed.

This method throws an IllegalArgumentException if source is null.

Parameters:

source - The Object that originated the event

runnable - The Runnable whose run() method will be executed

listener - The Runnable whose run() method will be called after the InvocationEvent was dispatched or disposed

catchThrowables - Specifies whether dispatch should catch Throwable when executing the Runnable's run() method, or should instead propagate those Throwables to the EventDispatchThread's dispatch loop

Throws:

IllegalArgumentException - if source is null

InvocationEvent

protected InvocationEvent(Object source,
 int id,
 Runnable runnable,
 Object notifier,
 boolean catchThrowables)

Constructs an InvocationEvent with the specified source and ID which will execute the runnable's run() method when dispatched. If notifier is non-null, notifyAll() will be called on it immediately after run() has returned or thrown an exception.

This method throws an IllegalArgumentException if source is null.

Parameters:

source - The Object that originated the event

id - An integer indicating the type of event. For information on allowable values, see the class description for InvocationEvent

runnable - The Runnable whose run() method will be executed

notifier - The Object whose notifyAll method will be called after Runnable.run has returned or thrown an exception or after the event was disposed

catchThrowables - Specifies whether dispatch should catch Throwable when executing the Runnable's run() method, or should instead propagate those Throwables to the EventDispatchThread's dispatch loop

Throws:

IllegalArgumentException - if source is null

See Also:

• EventObject.getSource()
• AWTEvent.getID()

Method Details

dispatch

public void dispatch()

Executes the Runnable's run() method and notifies the notifier (if any) when run() has returned or thrown an exception.

Specified by:

dispatch in interface ActiveEvent

See Also:

• isDispatched()

getException

public Exception getException()

Returns any Exception caught while executing the Runnable's run() method.

Returns:

A reference to the Exception if one was thrown; null if no Exception was thrown or if this InvocationEvent does not catch exceptions

getThrowable

public Throwable getThrowable()

Returns any Throwable caught while executing the Runnable's run() method.

Returns:

A reference to the Throwable if one was thrown; null if no Throwable was thrown or if this InvocationEvent does not catch Throwables

Since:

1.5

getWhen

public long getWhen()

Returns the timestamp of when this event occurred.

Returns:

this event's timestamp

Since:

1.4

isDispatched

public boolean isDispatched()

Returns true if the event is dispatched or any exception is thrown while dispatching, false otherwise. The method should be called by a waiting thread that calls the notifier.wait() method. Since spurious wakeups are possible (as explained in Object.wait()), this method should be used in a waiting loop to ensure that the event got dispatched:

     while (!event.isDispatched()) {
         notifier.wait();
     }
 

If the waiting thread wakes up without dispatching the event, the isDispatched() method returns false, and the while loop executes once more, thus, causing the awakened thread to revert to the waiting mode.

If the notifier.notifyAll() happens before the waiting thread enters the notifier.wait() method, the while loop ensures that the waiting thread will not enter the notifier.wait() method. Otherwise, there is no guarantee that the waiting thread will ever be woken from the wait.

Returns:

true if the event has been dispatched, or any exception has been thrown while dispatching, false otherwise

Since:

1.7

See Also:

• dispatch()
• notifier
• catchExceptions

paramString

public String paramString()

Returns a parameter string identifying this event. This method is useful for event-logging and for debugging.

Overrides:

paramString in class AWTEvent

Returns:

A string identifying the event and its attributes