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

[Kevin Rushforth]

Hi Neal,

You are correct. The JavaFX Application Thread is the event thread for 
JavaFX. It processes input events, pulses, animations, and Runnables 
that are submitted via runLater. Other than the special case when a 
nested event loop is spun up (e.g., showAndWait()) a new runnable or 
event will not be processed until the current one has returned to the 
event loop.

-- Kevin


ngalarneau at ABINITIO.COM wrote:
> Steve,
>
> 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.
>
>
> Neil
>
>
>
>
> From:   Stephen F Northover <steve.x.northover at oracle.com>
> To:     ngalarneau at ABINITIO.COM, openjfx-dev at openjdk.java.net, 
> Date:   11/03/2014 09:58 AM
> Subject:        Re: Questions about Platform.runLater() and 
> Application.start()
>
>
>
> 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.
>
> Steve
>
> 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 
>>     
> the
>   
>> 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 
>>     
> the
>   
>> 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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