Class EventQueueMonitor

java.lang.Object

com.sun.java.accessibility.util.EventQueueMonitor

All Implemented Interfaces:: AWTEventListener, EventListener

public class EventQueueMonitor extends Object implements AWTEventListener

The EventQueueMonitor class provides key core functionality for Assistive Technologies (and other system-level technologies that need some of the same things that Assistive Technology needs).

See Also:

Constructor Summary

Constructor	Description
`EventQueueMonitor()`	Create a new `EventQueueMonitor` instance.

Method Summary

Modifier and Type	Method	Description
`static void`	`addGUIInitializedListener(GUIInitializedListener l)`	Adds the specified listener to be notified when the GUI subsystem is initialized.
`static void`	`addTopLevelWindowListener(TopLevelWindowListener l)`	Adds the specified listener to be notified when a top level window is created or destroyed.
`void`	`eventDispatched(AWTEvent theEvent)`	Handle events as a result of registering a listener on the `EventQueue` in `maybeInitialize()`.
`static Accessible`	`getAccessibleAt(Point p)`	Obtain the `Accessible` object at the given point on the Screen.
`static Point`	`getCurrentMousePosition()`	Return the last recorded position of the mouse in screen coordinates.
`static Window[]`	`getTopLevelWindows()`	Return the list of top level Windows in use in the Java Virtual Machine.
`static Window`	`getTopLevelWindowWithFocus()`	Return the top level `Window` that currently has keyboard focus.
`static boolean`	`isGUIInitialized()`	Says whether the GUI subsystem has been initialized or not.
`static void`	`maybeInitialize()`	Tell the `EventQueueMonitor` to start listening for events.
`static void`	`removeGUIInitializedListener(GUIInitializedListener l)`	Removes the specified listener to be notified when the GUI subsystem is initialized.
`static void`	`removeTopLevelWindowListener(TopLevelWindowListener l)`	Removes the specified listener to be notified when a top level window is created or destroyed.

Methods declared in class Object

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

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()`	Returns a string representation of the object.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

EventQueueMonitor

public EventQueueMonitor()

Create a new EventQueueMonitor instance. Normally, this will be called only by the AWT Toolkit during initialization time. Assistive technologies should not create instances of EventQueueMonitor by themselves. Instead, they should either refer to it directly via the static methods in this class, e.g., getCurrentMousePosition() or obtain the instance by asking the Toolkit, e.g., Toolkit.getSystemEventQueue().

Method Details

maybeInitialize

public static void maybeInitialize()

Tell the EventQueueMonitor to start listening for events.

eventDispatched

public void eventDispatched(AWTEvent theEvent)

Handle events as a result of registering a listener on the EventQueue in maybeInitialize().

Specified by:: eventDispatched in interface AWTEventListener
Parameters:: theEvent - the event to be processed

getAccessibleAt

public static Accessible getAccessibleAt(Point p)

Obtain the Accessible object at the given point on the Screen. The return value may be null if an Accessible object cannot be found at the particular point.

Parameters:: p - the point to be accessed
Returns:: the Accessible at the specified point

isGUIInitialized

public static boolean isGUIInitialized()

Says whether the GUI subsystem has been initialized or not. If this returns true, the assistive technology can freely create GUI component instances. If the return value is false, the assistive technology should register a GUIInitializedListener and wait to create GUI component instances until the listener is called.

Returns:

true if the GUI subsystem has been initialized

See Also:

addGUIInitializedListener

public static void addGUIInitializedListener(GUIInitializedListener l)

Adds the specified listener to be notified when the GUI subsystem is initialized. Assistive technologies should get the results of isGUIInitialized() before calling this method.

Parameters:

l - the listener to add

See Also:

removeGUIInitializedListener

public static void removeGUIInitializedListener(GUIInitializedListener l)

Removes the specified listener to be notified when the GUI subsystem is initialized.

Parameters:

l - the listener to remove

See Also:

addTopLevelWindowListener

public static void addTopLevelWindowListener(TopLevelWindowListener l)

Adds the specified listener to be notified when a top level window is created or destroyed.

Parameters:

l - the listener to add

See Also:

removeTopLevelWindowListener

public static void removeTopLevelWindowListener(TopLevelWindowListener l)

Removes the specified listener to be notified when a top level window is created or destroyed.

Parameters:

l - the listener to remove

See Also:

getCurrentMousePosition

public static Point getCurrentMousePosition()

Return the last recorded position of the mouse in screen coordinates.

Returns:: the last recorded position of the mouse in screen coordinates

getTopLevelWindows

public static Window[] getTopLevelWindows()

Return the list of top level Windows in use in the Java Virtual Machine.

Returns:: an array of top level Windows in use in the Java Virtual Machine

getTopLevelWindowWithFocus

public static Window getTopLevelWindowWithFocus()

Return the top level Window that currently has keyboard focus.

Returns:: the top level Window that currently has keyboard focus

© 1993, 2025, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.