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Class 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

Fields

INVOCATION_FIRST

public static final int INVOCATION_FIRST

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

INVOCATION_DEFAULT

public static final int INVOCATION_DEFAULT

The default id for all InvocationEvents.

INVOCATION_LAST

public static final int INVOCATION_LAST

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

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.

Constructors

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 RunnableRunnable 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()

Methods

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

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