Java Reference
In-Depth Information
A remote object must guard against two thread safety hazards: properly coordinating access
to state that may be shared with other objects, and properly coordinating access to the state
of the remote object itself (since the same object may be called in multiple threads simultan-
eously). Like servlets, RMI objects should be prepared for multiple simultaneous calls and
must provide their own thread safety.
Swing and AWT.
GUI applications are inherently asynchronous. Users may select a menu
item or press a button at any time, and they expect that the application will respond promptly
even if it is in the middle of doing something else. Swing and AWT address this problem by
creating a separate thread for handling user-initiated events and updating the graphical view
presented to the user.
Swing components, such as
JTable
, are not thread-safe. Instead, Swing programs achieve
their thread safety by confining all access to GUI components to the event thread. If an ap-
plication wants to manipulate the GUI from outside the event thread, it must cause the code
that will manipulate the GUI to run in the event thread instead.
When the user performs a UI action, an event handler is called in the event thread to perform
whatever operation the user requested. If the handler needs to access application state that is
also accessed from other threads (such as a document being edited), then the event handler,
along with any other code that accesses that state, must do so in a thread-safe manner.
