Le 24/08/2010 10:57, [email protected] a écrit :
Changeset: 7e26538596be
Author: art
Date: 2010-08-24 12:54 +0400
URL: http://hg.openjdk.java.net/jdk7/awt/jdk/rev/7e26538596be
6949936: Provide API for running nested events loops, similar to what modal
dialogs do
Reviewed-by: ant, anthony
! src/share/classes/java/awt/Dialog.java
! src/share/classes/java/awt/EventDispatchThread.java
! src/share/classes/java/awt/EventQueue.java
+ src/share/classes/java/awt/SecondaryLoop.java
+ src/share/classes/java/awt/WaitDispatchSupport.java
+ test/java/awt/EventQueue/SecondaryLoopTest/SecondaryLoopTest.java
Hi all, nice to see that this kind of API find its way to jdk7.
The example provided in SecondaryLoop don't compile.
Here is a slightly modified version that compile.
JButton jButton = new JButton("Button");
jButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
EventQueue queue = Toolkit.getDefaultToolkit()
.getSystemEventQueue();
final SecondaryLoop loop = queue.createSecondaryLoop();
Runnable runnable = new Runnable() {
@Override
public void run() {
// Perform calculations
doSomethingUseful();
// Exit the loop
loop.exit();
}
};
// Spawn a new thread to do the work
Thread worker = new Thread(runnable);
worker.start();
// Enter the loop to block the current event
// handler, but leave UI responsive
if (!loop.enter()) {
// Report an error
}
}
});
About the API design, SecondaryLoop.enter is not reentrant so it's
an error to call it recursively. So enter() should throw a runtime exception
instead of returning false. I propose to use IllegalStateException.
SecondaryLoop is in my opinion a bad name, a for or a while is a loop,
in my opinion, SecondaryEventLoop is a better name.
Also, you don't provide a way to transfer any value from the computation
done in the thread back to the event queue thread like by example
the SwingWorker does.
I propose to change SecondaryEventLoop to:
public interface SecondaryEventLoop<V> {
public V enter();
public boolean exit(V value);
}
exit() can send a value that will be returned when enter() will end.
I also wonder if the return value of exit is useful.
exit can be called before enter() due to a race between enter() and exit(),
why a developer should care about that.
cheers,
Rémi
