Is happens-before relation given in case of invokeLater() or invokeAndWait?

问题

Pretty sure it is this way - but I like to know for sure - is happens-before relation given in case of invokeLater() or invokeAndWait()?

The methods are defined in (SwingUtilities respectively) AWT.EventQueue. I guess there is synchronization involved when something is entered in the EventQueue and hence as result of the synchronization, the happens-before relation and finally the visibility is given.

But is it really that way? (and where can I find that information?)

---

e.g. inside some worker thread

    ...
    *<1> heavy computation modifying lots of DATA*
    ...
    SwingUtilities.invokeLater(
        new Runnable() {
            @Override
            public void run() {
                *<2> is visibility of modified DATA guaranteed?*
            }
        }
    );

---

e.g. inside some thread

    ...
    SwingUtilities.invokeAndWait(
        new Runnable() {
            @Override
            public void run() {
                ...
                *<1> change some DATA*
            }
        }
    );
    *<2> is visibility of modified DATA guaranteed?*

回答1:

In short: yes, there is a happens-before relationship imposed between actions of the thread calling invokeLater/invokeAndWait and actions on the EDT of the runnable thereby submitted. Without that the sanity of the whole API would be at stake.

Unfortunately, it is hard to come by any authoritative source which would confirm that. That happens with a lot of stuff regarding Swing and concurrency.

For a bit more information, refer to this answer by trashgod, a long-time Swing guru.

来源：https://stackoverflow.com/questions/21147240/is-happens-before-relation-given-in-case-of-invokelater-or-invokeandwait