java.lang.Object
- java.awt.EventQueue

public class EventQueue extends java.lang.Object

EventQueue is a platform-independent class that queues events, both from the underlying peer classes and from trusted application classes.
It encapsulates asynchronous event dispatch machinery which extracts events from the queue and dispatches them by calling dispatchEvent(AWTEvent) method on this EventQueue with the event to be dispatched as an argument. The particular behavior of this machinery is implementation-dependent. The only requirements are that events which were actually enqueued to this queue (note that events being posted to the EventQueue can be coalesced) are dispatched:

Sequentially.
That is, it is not permitted that several events from this queue are dispatched simultaneously.
In the same order as they are enqueued.
That is, if AWTEvent A is enqueued to the EventQueue before AWTEvent B then event B will not be dispatched before event A.

Some browsers partition applets in different code bases into separate contexts, and establish walls between these contexts. In such a scenario, there will be one EventQueue per context. Other browsers place all applets into the same context, implying that there will be only a single, global EventQueue for all applets. This behavior is implementation-dependent. Consult your browser's documentation for more information.
For information on the threading issues of the event dispatch machinery, see AWT Threading Issues.

Since:

1.1

Static Methods
	Modifier and Type	Static Method and Description
	getCurrentEvent	`static AWTEvent` getCurrentEvent() Returns the the event currently being dispatched by the `EventQueue` associated with the calling thread. public static AWTEvent getCurrentEvent() Returns the the event currently being dispatched by the `EventQueue` associated with the calling thread. This is useful if a method needs access to the event, but was not designed to receive a reference to it as an argument. Note that this method should only be invoked from an application's event dispatching thread. If this method is invoked from another thread, null will be returned. Returns: the event currently being dispatched, or null if this method is invoked on a thread other than an event dispatching thread Since: 1.4
	getMostRecentEventTime	`static long` getMostRecentEventTime() Returns the timestamp of the most recent event that had a timestamp, and that was dispatched from the `EventQueue` associated with the calling thread. public static long getMostRecentEventTime() Returns the timestamp of the most recent event that had a timestamp, and that was dispatched from the `EventQueue` associated with the calling thread. If an event with a timestamp is currently being dispatched, its timestamp will be returned. If no events have yet been dispatched, the EventQueue's initialization time will be returned instead.In the current version of the JDK, only `InputEvent`s, `ActionEvent`s, and `InvocationEvent`s have timestamps; however, future versions of the JDK may add timestamps to additional event types. Note that this method should only be invoked from an application's `event dispatching thread`. If this method is invoked from another thread, the current system time (as reported by `System.currentTimeMillis()`) will be returned instead. Returns: the timestamp of the last `InputEvent`, `ActionEvent`, or `InvocationEvent` to be dispatched, or `System.currentTimeMillis()` if this method is invoked on a thread other than an event dispatching thread Since: 1.4 See Also: `InputEvent.getWhen()`, `ActionEvent.getWhen()`, `InvocationEvent.getWhen()`, `isDispatchThread()`
	invokeAndWait	`static void` invokeAndWait(java.lang.Runnable runnable) Causes `runnable` to have its `run` method called in the `dispatch thread` of `the system EventQueue`. public static void invokeAndWait(java.lang.Runnable runnable) throws java.lang.InterruptedException, java.lang.reflect.InvocationTargetException Causes `runnable` to have its `run` method called in the `dispatch thread` of `the system EventQueue`. This will happen after all pending events are processed. The call blocks until this has happened. This method will throw an Error if called from the `event dispatcher thread`. Parameters: `runnable` - the `Runnable` whose `run` method should be executed synchronously in the `event dispatch thread` of `the system EventQueue` Throws: `java.lang.InterruptedException` - if any thread has interrupted this thread `java.lang.reflect.InvocationTargetException` - if an throwable is thrown when running `runnable` Since: 1.2 See Also: `invokeLater(java.lang.Runnable)`, `Toolkit.getSystemEventQueue()`, `isDispatchThread()`
	invokeLater	`static void` invokeLater(java.lang.Runnable runnable) Causes `runnable` to have its `run` method called in the `dispatch thread` of `the system EventQueue`. public static void invokeLater(java.lang.Runnable runnable) Causes `runnable` to have its `run` method called in the `dispatch thread` of `the system EventQueue`. This will happen after all pending events are processed. Parameters: `runnable` - the `Runnable` whose `run` method should be executed asynchronously in the `event dispatch thread` of `the system EventQueue` Since: 1.2 See Also: `invokeAndWait(java.lang.Runnable)`, `Toolkit.getSystemEventQueue()`, `isDispatchThread()`
	isDispatchThread	`static boolean` isDispatchThread() Returns true if the calling thread is `the current AWT EventQueue`'s dispatch thread. public static boolean isDispatchThread() Returns true if the calling thread is `the current AWT EventQueue`'s dispatch thread. Use this method to ensure that a particular task is being executed (or not being) there. Note: use the `invokeLater(java.lang.Runnable)` or `invokeAndWait(java.lang.Runnable)` methods to execute a task in `the current AWT EventQueue`'s dispatch thread. Returns: true if running in `the current AWT EventQueue`'s dispatch thread Since: 1.2 See Also: `invokeLater(java.lang.Runnable)`, `invokeAndWait(java.lang.Runnable)`, `Toolkit.getSystemEventQueue()`

Constructors
Constructor and Description

EventQueue

EventQueue()

public EventQueue()

Constructors
	Constructor and Description
	EventQueue	EventQueue() public EventQueue()

Modifier and Type Method and Description

createSecondaryLoop

SecondaryLoop createSecondaryLoop()

Creates a new secondary loop associated with this event queue.

dispatchEvent

protected void dispatchEvent(AWTEvent event)

Dispatches an event.

protected void dispatchEvent(AWTEvent event)

Dispatches an event. The manner in which the event is dispatched depends upon the type of the event and the type of the event's source object:

Event Type	Source Type	Dispatched To
ActiveEvent	Any	event.dispatch()
Other	Component	source.dispatchEvent(AWTEvent)
Other	MenuComponent	source.dispatchEvent(AWTEvent)
Other	Other	No action (ignored)

Parameters:: event - an instance of java.awt.AWTEvent, or a subclass of it
Throws:: java.lang.NullPointerException - if event is null
Since:: 1.2

getNextEvent

AWTEvent getNextEvent()

Removes an event from the EventQueue and returns it.

peekEvent

AWTEvent peekEvent()

Returns the first event on the EventQueue without removing it.

peekEvent

AWTEvent peekEvent(int id)

Returns the first event with the specified id, if any.

pop

protected void pop()

Stops dispatching events using this EventQueue.

postEvent

void postEvent(AWTEvent theEvent)

Posts a 1.1-style event to the EventQueue.

push

void push(EventQueue newEventQueue)

Replaces the existing EventQueue with the specified one.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

SourceForge

Class EventQueue

Methods inherited from class java.lang.Object