Javafx embedded in swing multithreaded toolkit issue

Anthony Petrov anthony.petrov at
Wed Mar 21 12:12:04 PDT 2012

To rewrite your app completely in FX? :)

Seriously though, could you briefly describe the exact problem that 
you're trying to resolve?

As a general guideline to writing GUI apps, it is always recommended to 
not block the event processing thread under any circumstances. Please 
note that this requirement is true for almost every GUI toolkit out 
there, including native GUI APIs. Both Swing and FX are no exceptions. 
In other words, operations such as invokeAndWait() on the event thread 
should be avoided at all costs.

Indeed, in case of embedding FX scenes into Swing we have two unrelated 
GUI toolkits running at the same app, and as such synchronization 
between the states of components in these two toolkits is a challenging 
task. We, FX developers, do realize this. However, there doesn't seem to 
exist a simple solution for this issue. Best advice is to try and use 
the invokeLater()/runLater() kinds of methods only.

best regards,

On 3/21/2012 10:58 PM, Pedro Duque Vieira wrote:
> Hi Anthony,
> Ok, I see.. So is there any solution to this problem?
> Thanks,
> On Wed, Mar 21, 2012 at 6:55 PM, Anthony Petrov 
> <anthony.petrov at <mailto:anthony.petrov at>> wrote:
>     Hi Pedro,
>     Tooltips and combo-box popups are examples of scenes that use
>     top-level windows. Even if the component showing the popup is
>     embedded into a JFXPanel, its popups are always top-level windows.
>     --
>     best regards,
>     Anthony
>     On 3/21/2012 8:51 PM, Pedro Duque Vieira wrote:
>         ... or couldn't it be a requirement, to have scenes only embedded on
>         JFXPanel?
>         On Wed, Mar 21, 2012 at 2:04 PM, Pedro Duque Vieira <
>         pedro.duquevieira at
>         <mailto:pedro.duquevieira at>> wrote:
>             Hi Artem, thanks for the reply.
>             If FX lived on Swing event dispatch thread, all the FX
>             top-level windows
>                 (that are not embedded into JFXPanel) would never
>                 receive any events.
>             In this scenario (embedding javafx in swing), what
>             situations would there
>             be on which top level windows aren't embedded into JFXPanel?
>             I think this problem is very important. If things continue
>             as they are,
>             embedding javafx into swing will be virtually impossible as
>             this blog post
>             illustrates:
>             <>
>             Cheers,
>             On Wed, Mar 21, 2012 at 9:23 AM, Artem Ananiev
>             <artem.ananiev at
>             <mailto:artem.ananiev at>>__wrote:
>                 On 3/21/2012 6:17 AM, Pedro Duque Vieira wrote:
>                     Hi,
>                     I've been working for a while on a swing app that
>                     has a javafx scene
>                     embedded on it.
>                     So in this scenario we have two UI threads, one for
>                     the swing part and
>                     one
>                     for the javafx scene (the application thread).
>                     This situation creates a multithreaded ui toolkit
>                     which is basically a
>                     nightmare for development.
>                     I don't know if this is possible but it I think it
>                     would be best to merge
>                     the swing and the javafx application thread into one
>                     when on this
>                     scenario.
>                 In JavaFX/SWT bridge (FXCanvas) we do exactly this: FX
>                 application thread
>                 is the same as SWT event thread. Unfortunately, in
>                 JavaFX/Swing case it is
>                 not possible.
>                 In a few words, Swing event dispatch thread only pumps
>                 Java events. All
>                 the native events are dispatched on another thread,
>                 which is called AWT
>                 toolkit thread. This thread cannot be accessed from
>                 outside of AWT, it's
>                 not a part of public API. If FX lived on Swing event
>                 dispatch thread, all
>                 the FX top-level windows (that are not embedded into
>                 JFXPanel) would never
>                 receive any events.
>                 Thanks,
>                 Artem
>                  One other possible solution that comes to my mind  and
>                 also a much
>                     simpler
>                     and quicker one is to add a
>                     Platform.invokeAndWait(like what exists on
>                     swing) alongside the Platform.runLater to the javafx
>                     API.
>                     And each time I want to invoke something on the
>                     javafx App thread from
>                     the
>                     swing ui thread I call invokeAndWait instead of
>                     runLater. So effectively
>                     the two UI threads become only one, because they are
>                     not running
>                     concurrently but sequentially instead.
>             --
>             Pedro Duque Vieira
> -- 
> Pedro Duque Vieira

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