Documentation Contents

# AWT Enhancements in the Java SE 1.4

1.4.2 Bug Fixes
1.4.1 Bug Fixes
New Focus Subsystem
Deprecated Focus Methods
ActionEvents (and Other Events) Need Timestamps
Headless Support
Window Centering API Required for Multiscreen Support
The New Fullscreen Exclusive Mode API
Sync Out of Range Error From Video Driver Under Windows NT Undecorated Frames
Mouse Wheel Support
Programmatic Zooming of `Frame`s
Dynamic Layout During Resize
Access to Component Listener Lists
Changes to Drag and Drop
64-Bit Compliance on Solaris
Inconsistent DLLs Warning
Removal of the `DrawingSurface` API
New InputEvent Key Modifiers
Change in Drop Down Behavior for Choice Menus
Choice Component Now Obeys Layout Manager Constraints

1.4.2 Bug Fixes

4648702: On Microsoft Windows 2000 and Windows XP, a `TextArea` will sometimes display only a vertical scrollbar, even though the `SCROLLBARS_BOTH` field is set to `true`.

4636311: Modal dialogs may hang when run from a `Runnable` on release 1.3.1 and 1.4.

4385243: Unable to input text in Microsoft Windows locales that don't have an ANSI code page (such as Hindi).

1.4.1 Bug Fixes

4690831: Game applets fail to repaint properly with Internet Explorer.

4627627: Focus traversal keys moved from awt.properties to Preferences API.

4636548/ 4639735: Crash of release 1.4 when screensaver on Microsoft Windows 2000 is activated.

4379138: Problems on Linux with key events for some dead keys.

4627542: Swing applications don't support international keyboards under Linux.

4395157: Under Linux on 1.3, can't type "%" in applets.

4669873: A drag and drop bug, reported on hopper-beta under Microsoft Windows, caused an application to briefly freeze during DnD and is fixed in the final release of 1.4.1.

New Focus Subsystem

The bugtraq report that corresponds to this change is: 4290675.

A new focus subsystem replaces the previous focus architecture and addresses many focus-related bugs caused by platform inconsistencies, and incompatibilities between AWT and Swing components. See the new Focus Model Specification for further details.

See the javadoc here.

Headless Support

The bugtraq report that corresponds to this change is: 4281163.

Many environments, such as mainframe machines and dedicated servers, do not support a display, keyboard, or mouse. Headless support is enabled by the new `GraphicsEnvironment` methods `isHeadless` and `isHeadlessInstance`. These methods indicate whether a display, keyboard, and mouse can be supported in a graphics environment.

The API changes for headless include:

- A new public exception class, `java.awt.HeadlessException`, is introduced. It is derived from `UnsupportedOperationException`, which derives from `RuntimeException`, so that existing implementations of methods that throw the new exception will not require signature changes.
- Two new methods, are added to `java.awt.GraphicsEnvironment`.

          public static boolean isHeadless()

          public boolean isHeadlessInstance()

- The constructors of `Applet` and all heavyweight components (*) are changed to throw `HeadlessException` if a display, keyboard, and mouse are not supported by the toolkit implementation. All javadoc tags on all constructors are changed to reflect this `RuntimeException`.
- The `Robot` constructor throws an `AWTException` if a display, keyboard, and mouse are not supported by the toolkit implementation.
- Many of the methods in `Toolkit` and `GraphicsEnvironment`, with the exception of fonts, imaging, and printing, are changed to throw `HeadlessException` if a display, keyboard, and mouse are not supported. All the javadoc tags on these methods are changed to reflect this `RuntimeException`.
- Other methods that may be affected by lack of display, keyboard, or mouse support, are changed to throw `HeadlessException`.
- It should be worth noting that the `HeadlessException` is thrown if and only if `isHeadless` returns true, and that all javadoc comments should specify this.

(*)`Applet`, `Button`, `Checkbox`, `Choice`, `FileDialog`, `Label`, `List`, `Menu`, `MenuBar`, `MenuComponent`, `MenuItem`, `PopupMenu`, `Scrollbar`, `ScrollPane`, `TextArea`, `TextComponent`, `Frame`, `Window`, `Dialog`, `JApplet`, `JFrame`, `JWindow`, `JDialog`, and `TextField`. `Canvas` and `Panel` do not need to throw this exception since these can be given empty peers and treated as lightweights.

To run our environment with a headless implementation, the follow property may be specified at the `java` command line:

      -Djava.awt.headless=true

If this property is not specified and a display, keyboard, and mouse are not supported, then headless implementation is used by default.

Source code should check for headless, so that the exception may be caught gracefully. For example, see the following pre-headless implementation of the class `Foo`:

    class Foo {
      static Choice c = new Choice();  // could throw HeadlessException
    }

The new and improved implementation of `Foo` should be placed in a static block:

    class Foo {
      static Choice c;
      static {
        try {
          c = new Choice();
        catch (HeadlessException e) {
            ...
        }
      }
    }

The New Fullscreen Exclusive Mode API

The bugtraq report that corresponds to this change is: 4189326.

The new full-screen exclusive mode API supports high performance graphics by suspending the windowing system so that drawing can be done directly to the screen. Full screen mode, which is entirely different from simply taking an AWT `Frame`, `Window`, or `Dialog` and expanding it to fit the screen, is a graphics mode whereby the application takes entire control over the contents of video memory. The application tells the graphics card what to draw, how to draw it, and when to draw it. This mode is not always available. On some operating systems, it may not be implemented at all. On other operating systems, it may only be available if the capability is supported by the graphics card. Nevertheless, this mode is critical for performance and is necessary for enabling hardware page-flipping on Windows.

For a tutorial explaining how to use the full screen exclusive API mode with several code examples, see here.

API Changes:

- A new public final class, `java.awt.DisplayMode`, is introduced.
- Changes to `java.awt.GraphicsDevice`:

          public void setFullScreenWindow(Window w)

          public Window getFullScreenWindow()

          public boolean isDisplayChangeSupported()

          public void setDisplayMode(DisplayMode dm)

          public DisplayMode getDisplayMode()

          public DisplayMode[] getDisplayModes()

- The algorithm which handles direct video buffer control has been localized to a new class, `java.awt.image.BufferStrategy`.
- A new class `java.awt.BufferCapabilities` can be used when creating a buffer strategy. Likewise, a new class `java.awt.ImageCapabilities` is available to define the image capabilities of a specific configuration.
- An application programmer can create and use a buffer strategy from a `Canvas` or a `Window`. There are two buffer strategies that are supported as protected inner classes: `java.awt.Component.FlipBufferStrategy` and `java.awt.Component.BltBufferStrategy`. One of these two inner classes is used on the `Canvas` or `Window` when the `createBufferStrategy` method is called, depending on the `BufferCapabilities` object supplied when creating the strategy (if any). To get the buffer strategy used by a particular component, the `getBufferStrategy` method is used.

Sync Out of Range Error From Video Driver Under Windows NT

The bugtraq report that corresponds to this change is: 4452207.

If you have a Dell Optiplex GX110 using an Intel 810 Graphics Controller, under Windows NT, you may get a "sync out of range" message from the video driver if you change the display mode more than once and use a high display resolution. There is evidently a bug in the (DirectX) video driver that is causing this. There are several workarounds to this problem:

- Disable DirectDraw by using `-Dsun.java2d.noddraw=true` at the command line.
- Do not change the display resolution more than once during the lifetime of a program that is intended to run on this hardware.
- Disallow the following display modes on this hardware:

          1152 X 864     8       85
          1152 X 864     16      85
          1152 X 864     24      85

          1280 X 1024    8       70,72,75,85
          1280 X 1024    16      70,72,75,85
          1280 X 1024    24      70,75,85

          Bad Color (Unsatisfactory appearance in terms of color)

          1024 X 768     8       60,70,72,75,85

Undecorated Frames

The bugtraq report that corresponds to this change is: 4038769.

For certain applications having no native frame decorations makes sense. For example, applications that will run across many platforms and that require that the look and feel is the same, or when the programmer does not want the end-user coming in contact with the native operating system.

This release allows a Java application to turn off the creation of frame decorations; no native titlebar, system menu, border, or other native operating system dependent screen components appear when this mode is enabled. AWT and Swing components work transparently.

Changes to `java.awt.Frame`:

        public void setUndecorated(boolean undecorated)

        public boolean isUndecorated()

Changes to `java.awt.Dialog`:

        public void setUndecorated(boolean undecorated)

        public boolean isUndecorated()

Mouse Wheel Support

The bugtraq report that corresponds to this change is: 4289845.

The mouse wheel, with a scroll wheel in place of the middle mouse button, is enabled with new built-in Java support for scrolling via the mouse wheel. The `java.awt.event.MouseWheelEvent` class enables seamless support for mouse wheel scrolling in Java applications with no recompiling required. Also, a new `java.awt.event.MouseWheelListener` interface allows customization of mouse wheel behavior.

Note, for those using the mouse wheel on Linux, see here.

- Scrolling Behavior:
  - A scrollbar is considered "scrollable" if it is both showing and there is more content in the scrolling `Component` than can be displayed at once, such that the scroll thumb does not occupy the entire scroll track.
  - It is possible for a scrollbar to be showing, but not be scrollable. Usually this occurs when a scrollbar is set to always be displayed.
  - The scrollbar to be scrolled by the mouse wheel is determined as follows:
    - If only one scrollbar is scrollable, it will be scrolled.
    - If both a horizontal and a vertical scrollbar are scrollable, the vertical scrollbar will be scrolled.
  - Wheel scrolling may be disabled altogether using `setWheelScrollEnabled(false)`.
  - Up/away-from-user rotations cause vertical scroll bars to scroll upwards, and horizontal scrollbars to scroll to the left. Just the opposite is true for down/towards rotations.
  - No scrolling takes place if a scroll thumb is at the end of the scroll track.
- Heavyweight support:
  - Some native peers with integrated scroll bars can handle mouse wheel scrolling by themselves. Examples on Windows includes `TextArea`, `Choice`, `FileDialog`, and `List`. Such components will let their native peers handle wheel scrolling.
  - `Component`s which do not inherit any native mouse wheel behavior will propagate mouse wheel events up the `Container` hierarchy until a `Container` with `MouseWheelEvent`s enabled is found. This is typically a `ScrollPane`. Mouse wheel events are delivered to the `Component` with `MouseWheelEvent`s enabled.
  - Alternatively, client programmers may add `MouseWheelListener`s to customize what happens when the mouse wheel is moved while the mouse is over a `Component`. In the case of `Component`s that already have native handling of mouse wheel events, clients may consume the mouse wheel event to avoid native handling.
  - `java.awt.ScrollPane` is modified to have `MouseWheelEvent`s enabled by default. When a `ScrollPane` receives a `MouseWheelEvent`, it will properly scroll its contained `Component`. This functionality may be disabled with the new `setWheelScrollingEnabled` method.

- Lightweight Support:

  - Lightweight components will deliver mouse wheel events to their first ancestor with a `MouseWheelListener`.
  - `MouseWheelListener`s may be added to any `JComponent` for custom event handling.
  - `javax.swing.JScrollPane` is modified to properly scroll its viewed component. Like `java.awt.ScrollPane`, this may be disabled using `setWheelScrollingEnabled`.
- New API:

  In addition to the new class and new interface previously mentioned, there are some other changes to the API to support the mouse wheel.

  - Change to `java.awt.AWTEvent`:

            public final static long MOUSE_WHEEL_EVENT_MASK;

  - Changes to `java.awt.AWTEventMulticaster`:

            public void mouseWheelMoved(MouseWheelEvent e)

            public static MouseWheelListener add(MouseWheelListener a, MouseWheelListener b)

            public static MouseWheelListener remove(MouseWheelListener l, MouseWheelListener oldl)

  - Changes to `java.awt.Component`:

            public synchronized void addMouseWheelListener(MouseWheelListener l)

            public synchronized void removeMouseWheelListener(MouseWheelListener l)

  - Changes to `java.awt.ScrollPane`:

            public void setWheelScrollingEnabled(boolean handleWheel)

            public boolean isWheelScrollingEnabled()

  - Change to `java.awt.Robot`:

            public synchronized void mouseWheel(int wheelAmt)

- Linux Mouse Wheel Support:

  For Linux to recognize your mouse wheel, two modifications to the `/etc/X11/XF86Config` file are required. Under the "Pointer" section:

  - Add the line:

            ZAxisMapping 4 5

  - Change the protocol to: "imps/2" (this will vary depending on your particular wheel mouse).

Programmatic Zooming of `Frame`s

The bugtraq report that corresponds to this change is: 4071554.

Previously there was no way to zoom (or maximize) a `Frame` programmatically. This feature has been added to this release.

The new interface `java.awt.event.WindowStateListener` is introduced.

Changes to `java.awt.Frame`:

        public static final int MAXIMIZED_HORIZ;

        public static final int MAXIMIZED_VERT;

        public static final int MAXIMIZED_BOTH;

        public synchronized void setMaximizedBounds(Rectangle bounds)

        public Rectangle getMaximizedBounds()

        public synchronized void setExtendedState(int state)

        public synchronized int getExtendedState()

Changes to `java.awt.event.WindowEvent`:

        public static final int WINDOW_STATE_CHANGED;

        public WindowEvent(Window source, int id, Window opposite, int oldState, int newState)

        public WindowEvent(Window source, int id, int oldState, int newState)

        public int getOldState()

        public int getNewState()

Changes to `java.awt.AWTEvent`:

        public final static long WINDOW_STATE_EVENT_MASK;

Changes to `java.awt.Toolkit`:

        public boolean isFrameStateSupported(int state) throws HeadlessException

Changes to `java.awt.Window`:

        public synchronized void addWindowStateListener(WindowStateListener l)

        public synchronized void removeWindowStateListener(WindowStateListener l)

        public synchronized WindowStateListener[] getWindowStateListeners()

        protected void processWindowStateEvent(WindowEvent e)

Change to `java.awt.event.WindowAdapter`:

        public void windowStateChanged(WindowEvent e)

Changes to `java.awt.AWTEventMulticaster`:

        public static WindowStateListener add(WindowStateListener a, WindowStateListener b)

        public static WindowStateListener remove(WindowStateListener l, WindowStateListener oldl)

Dynamic Layout During Resize

The bugtraq report that corresponds to this change is: 4077991.

Previously, dynamic window resizing wasn't supported on all platforms. For example, on Windows NT, with solid resize on, resizing a window recalculated the layout only when the drag was finished. This has been fixed in this release with the addition of the new desktop property `awt.dynamicLayoutSupported`. When dynamic layout is enabled, a `Container` continually lays out its components as it resizes. If disabled, the layout will be validated after resizing has finished.

API changes to `java.awt.Toolkit`.

        public void setDynamicLayout(boolean dynamic)

        protected boolean isDynamicLayoutSet()

        public boolean isDynamicLayoutActive()

Access to Component Listener Lists

The bugtraq report that corresponds to this change is: 4290704.

Previously all of the state in an AWT component that could be written could also be read. For example, there are no write-only properties in the component API. Event listeners were a notable exception. AWT event listeners are managed according to the JavaBeans conventions with a pair of methods: `addXXXListener` and `removeXXXListener` for a listener that implements the `XXXEventListener` interface.

No access was provided to the listener lists themselves. The fields that contain the listener lists are package private and no method was provided that returns the contents of a listener list. This has caused some problems for Swing and other AWT clients.

To mitigate the problem in the Java 2 SDK, v1.3 release, we added a `getListeners` method to `Component` and to the Swing classes that defined listener lists. The `getListeners` method uses a class to specify a particular listener list. For example to get all of the listeners added with `addFocusListener`, one would write: `getListeners(FocusListener.class)`.

This particular approach to exposing listener lists was taken to minimize the overall change to the AWT/Swing public API. It was not intended to be a convention for all JavaBeans and it did not handle `PropertyChangeListener`s - which can be added to a single property, as in `addPropertyChangeListener("myProperty", myListener)`. For this release, we have designed a more complete solution to accessing event listeners. The two conceptual changes are:

- The addition of a `getFooListeners` method to the add/remove convention in AWT and Swing classes.
- Support for `PropertyChangeListener`s and `VetoableChangeListener`s, including those which listen to a single property, using the new `java.util.EventListenerProxy` class.

There is a new `java.awt.event.AWTEventListenerProxy` class.

API Changes to `java.awt.Toolkit`:

        public PropertyChangeListener[] getPropertyChangeListeners()

        public synchronized PropertyChangeListener[] getPropertyChangeListeners(String propertyName)

        public AWTEventListener[] getAWTEventListeners()

        public AWTEventListener[] getAWTEventListeners(long eventMask)

Changes to Drag and Drop

The bugtraq reports that corresponds to this change are: 4407057 and 4426750.

In the Solaris and Linux releases of Java 2 Standard Edition, SDK 1.3, several of the AWT heavyweight `Component`s exhibited default drag behavior via the middle mouse button, even if the application did not identify these `Components` as `DragSource`s via the `java.awt.dnd API`. These `Component`s were implemented using Motif peers, and Motif provides middle button drag behavior for these peers by default.

Because of the design of the AWT, and because of bugs in the Motif library, this default behavior has been the source of numerous stability problems. Rather than continue to risk the stability of AWT and Drag & Drop for a niche feature, we have chosen to disable this feature explicitly in our implementations.

Developers can still identify these `Component`s as `DragSource`s in their applications using the `java.awt.dnd API`. This is both functional and supported. This approach is superior to relying upon default Motif behavior in any case, because it enables drag support for these `Component`s on all platforms, not just Solaris and Linux.

64-Bit Compliance on Solaris Machines

The bugtraq report that corresponds to this change is: 4295833.

64-bit Solaris applications use 64 bits to address memory instead of 32. This allows larger applications by providing a much larger virtual memory space. For this release, AWT has been brought up to 64-bit compliance. For more information, see here.

Inconsistent DLLs Warning

The bugtraq report that corresponds to this change is: 4414004.

If you have installed English VC++ 6.0 onto a machine that also has Asian Windows NT installed, you may encounter strange artifacts when rendering Asian text in the `TextArea` component. You may also see this problem if you have installed Microsoft Exchange or Microsoft Office 97 onto a machine running Asian Windows NT 4.0. Although this problem was reported on the Japanese version of Windows NT, it will probably occur on other non-Latin versions of NT as well, such as Chinese or Korean.

The problem was caused when the installation of those programs replaced the Asian Riched32.dll with the English version. The problem can be corrected by replacing Riched32.dll with the Asian version.

Removal of the Drawing Surface API

The bugtraq report that corresponds to this change is: 4293646.

The `sun.awt.DrawingSurface` API has been removed. It was never made public, but some developers have been using it. The functionality has been replaced by the JAWT. For more information, see the AWT Native Interface description.

Window Centering API Required for Multiscreen Support

The bugtraq report that corresponds to this change is: 4463949.

Xinerama-aware applications running on multi-headed systems have caused problems which have resulted in a variety of bug reports. Some multi-headed environments use monitors with little or no borders, which can be butted up against one another such that the resulting effect is one mammoth display. In this case, a "properly" centered window may span multiple screens. Other multi-headed environments use regular CRT monitors, with several inches of packaging between the actual display areas. In this case, a window spanning multiple screens produces a disconcerting effect, especially if the window cannot be dragged onto one monitor or the other (the Solaris login screen, for example). In short there was no way to tell where to center a window in a Xinerama environment.

To address this problem, the X group has added API which allows Xinerama users to specify where they want "centered" windows to be centered, and allows developers of Xinerama-aware applications to code accordingly.

Prior to this release, the way to center a window has been to center it within the bounds of the default `GraphicsDevice`, like this:

        bounds = getDefaultScreenDevice().getDefaultConfiguration().getBounds();
        frame.setLocation(bounds / 2 - size of window / 2);

This code would center the windows "correctly" on Xinerama systems where windows should be centered to the entire Xinerama coordinate space.

As of this release, post 4356756-fix JDKs will center windows "correctly" on Xinerama systems where windows should be centered within the first display.

To accomplish this, the `getCenterPoint` method has been added to `GraphicsEnvironment` .

This method works as follows on various platforms:

- Microsoft Windows/Macintosh:
  These platforms include all monitors in a single virtual coordinate space. However, there is one "primary" display (on Microsoft Windows the primary display contains the task bar, on the Mac, the menubar). Here, `getCenterPoint` returns the coordinates of the center of the primary display.
- X-Window, non-Xinerama
  Each display has its own coordinate system; the upper-left corner of every display is 0.0. Again, there is a "first" display. Here, `getCenterPoint` returns the center point of the primary display.
- X-Window, Xinerama
  All monitors share a single virtual coordinate space, as on Microsoft Windows. However, it is possible for the user to specify through X resources where windows should be centered. If these resources are set, `getCenterPoint` reflects their value. Otherwise, it returns the point at the center of the virtual coordinate space. (In practice, this will almost always be set - CDE sets it by default.)

As of JDK 1.4, the correct code for centering is:

        frame.setLocation(getCenterPoint() - size of window / 2);

The other method added to `GraphicsEnvironment` is `getMaximumWindowBounds`. Both `getCenterPoint` and `getMaximumWindowBounds` throw a `HeadlessException` when in Headless mode.

New InputEvent Key Modifiers

The bugtraq reports that corresponds to this change are: 4387938 and 4421515.

Previously, the `InputEvent` modifiers had the same values for keyboard and mouse buttons. In certain situations there was no way to distinguish which one was pressed or when more than one was held simultaneously. These situations included cases when more than one mouse button was down at the same time, or when a modifier key was used to modify a mouse event.

To address this deficiency, the following constants were added to `InputEvent`:

- `SHIFT_DOWN_MASK`
- `CTRL_DOWN_MASK`
- `META_DOWN_MASK`
- `ALT_DOWN_MASK`
- `ALT_GRAPH_DOWN_MASK`
- `BUTTON1_DOWN_MASK`
- `BUTTON2_DOWN_MASK`
- `BUTTON3_DOWN_MASK`

The following methods were added to `InputEvent`:

- `getModifiersEx`
- `getModifiersExText`

The class spec for `MouseEvent` was updated. The following constants were also added to `MouseEvent`:

- `NOBUTTON`
- `BUTTON1`
- `BUTTON2`
- `BUTTON3`

These methods in `MouseEvent` were added:

- `MouseEvent(Component source, int id, long when, int modifiers, int x, int y, int clickCount, boolean popupTrigger, int button)`
- `getButton`
- `getMouseModifiersText`

`DragSourceDragEvent` has the new method `getGestureModifiersEx`.

Change in Drop Down Behavior for Choice Menus

The bugtraq report that corresponds to this change is: 4462677.

The `Choice` drop down menu behavior has changed from JDK 1.3.1 to 1.4. In 1.3.1, you could click anywhere on the choice bar and the menu would drop down. In 1.4, you must click on the arrow selector on the right hand side of the `Choice` bar. Clicking anywhere else on the `Choice` bar has no effect. Also, the symbol on the `Choice` bar has changed from a bar to an arrow/bar combination. Finally, if the drop down menu extends outside of the parent, when clicking on that area, the application underneath is brought to the foreground. This happens on Solaris, not Windows.

Choice Component Now Obeys Layout Manager Constraints

The bugtraq report that corresponds to this change is: 4288285.

In releases prior to 1.4, the AWT `Choice` widget sometimes ignored the size that the layout manager told it to be. As of this release, it now obeys the layout manager constraints.

Deprecated Focus Methods

The bugtraq report that corresponds to this change is: 4476300.

The new focus subsystem, introduced in this release, introduced a new architecture and a new terminology for handling keyboard focus in sophisticated AWT and Swing applications. Prior to this project, many of the focus-related APIs were inconsistent in usage and termonology, were improperly documented, and led to poorly designed UIs. Now that the new architecture is in place, the most egregious of these APIs has been deprecated.

The following constants and methods have been deprecated:

- `javax.swing.FocusManager.FOCUS_MANAGER_CLASS_PROPERTY`
- `javax.swing.FocusManager.disableSwingFocusManager()`
- `javax.swing.FocusManager.isFocusManagerEnabled()`
- `javax.swing.JComponent.requestDefaultFocus()`
- `javax.swing.JComponent.isManagingFocus()`
- `javax.swing.JComponent.setNextFocusableComponent(Component)`
- `javax.swing.JComponent.getNextFocusableComponent()`
- `java.awt.Component.isFocusTraversable()`
- `java.awt.Component.hasFocus()`
- `javax.swing.SwingUtilities.findFocusOwner(Component)`

ActionEvents (and Other Events) Need Timestamps

The bugtraq report that corresponds to this change is: 4434193.

The new focus architecture includes a type-ahead mechanism that ensures that subsequent `KeyEvent`s that follow a `KeyEvent` that initiates a focus transfer are not delivered until the transfer is completed. The design for this feature is based on the UTC timestamps of the various events. Events with timestamps later than that of the initiating event are enqueued pending resolution of the transfer; events with earlier timestamps are not.

To implement this feature, the focus code keeps track of the timestamp of the event currently being handled. If a focus change is initiated during this handling, the timestamp is available for use. However, if the current event does not have a timestamp, then the current system time is used. This time is usually too far ahead of the time that the event actually occurred to be of any real use. As a result, the type-ahead mechanism fails, and `KeyEvent`s are delivered before the focus transfer is completed.

The most common case where we encountered this problem was with `ActionEvent`s. `ActionEvent`s are high-level, semantic events generated in response to underlying `InputEvent`s. While the `InputEvent`s had timestamps associated with them, the `ActionEvent`s did not. The `ActionEvent` API has therefore been expanded to accomodate a timestamp and the implementation has been updated so that an `ActionEvent`'s timestamp is equal to that of its underlying `InputEvent`.

The following methods have been added to `ActionEvent`:

- `ActionEvent(Object source, int id, String command, long when, int modifiers)`
- `getWhen`

The following `ActionEvent` methods were modified:

- `ActionEvent(Object source, int id, String command)`
- `ActionEvent(Object source, int id, String command, int modifiers)`

The `getWhen` method was added to `InvocationEvent`.

The `InvocationEvent` constructors `InvocationEvent(Object, Runnable)` and `InvocationEvent(Object, Runnable, Object, boolean)` were modified.

A new constructor `InputMethodEvent(Component, int, long, AttributedCharacterIterator, int, TextHitInfo, TextHitInfo)` was added to `InputMethodEvent`, as well as the `getWhen` method.

The following `InputMethodEvent` constructors have been modified:

- `InputMethodEvent(Component, int, AttributedCharacterIterator, int, TextHitInfo, TextHitInfo)`
- `InputMethodEvent(Component, int, TextHitInfo, TextHitInfo)`.

Finally, the following methods were added to `EventQueue`:

- `getMostRecentEventTime`
- `getCurrentEvent`

Copyright © 1993, 2015, Oracle and/or its affiliates. All rights reserved.
Contact Us