Questions about Platform.runLater() and Application.start()

ngalarneau at ABINITIO.COM ngalarneau at ABINITIO.COM
Wed Nov 5 16:18:37 UTC 2014


Thank you for that important addition.

Is it true that this, also, is not a special case?

In other words, is this how it works?
 - the input queue contains both Events and Runnables (from runLater() and 
the first one containing a call to Application.start())
 - one item is processed from the input queue at a time
 - if the processing of that item does a Dialog.showAndWait(), then:
 - - the processing of that item is suspended (the thread blocks?) until 
showAndWait() returns and
 - - a new item processor picks the next item off of the input queue & 
starts processing it

It looks like the "JavaFX Application Thread" is the item processor.


From:   Stephen F Northover <steve.x.northover at>
To:     ngalarneau at ABINITIO.COM, openjfx-dev at, 
Date:   11/03/2014 09:58 AM
Subject:        Re: Questions about Platform.runLater() and 

Hi there,

If you en-queue a runnable in start() it will not run until start() 
completes unless you open a dialog in start() that waits for a result 
before proceeding.  In that case, your runnable will run. You are 
correct about runnables and input events being part of the input queue 
for the application thread.  Threads are not interrupted to run code.


On 2014-11-03, 8:49 AM, ngalarneau at ABINITIO.COM wrote:
> Hello,
> Is there documentation that describes somewhere how Platform.runLater() 
> Application.start() interact?
> My impression is that (roughly speaking):
>   - there is an EventQueue (to use the Swing terminology).
>   - the EventQueue holds both UI events (like mouse click) as well as 
> Runnables enqueued by runLater().
>   - the first (?) event put in the EventQueue is a Runnable representing
> Application.start().
> My impression is, therefore, that any Runnables enqueued during
> Application.start() won't be run until after start() completes.
> This behavior is the same as one runLater() not interrupting another
> runLater().
> Is this sort of stuff documented somewhere?
> Is this the right way to think about this part of the system? (even if 
> implementation is different)
> Are there other special things to be aware of about Application.start()?
> Thanks,
> Neil
> P.S. I am using javafx.concurrent.Service & Task and am hitting some
> issues.

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