Incremental updates from Tasks

Richard Bair richard.bair at
Mon Jan 9 15:12:49 PST 2012

I've attached the latest full patch with tests to the issue ( I'll retarget it to 2.2 unless somebody is available to do an in depth review and let me know what you think. I think it is all set and ready to go, the only thing that kind of bothers me is the name ObservableListTask and the "process" name, since I have used "update" for the same functionality in Task / TaskBase.


On Jan 6, 2012, at 3:40 PM, Richard Bair wrote:

> I tried the following. I created a TaskBase, and moved almost everything from Task to TaskBase. Task now extends TaskBase, and adds:
> 	updateValue(V value);
> 	abstract V call() throws Exception;
> It is entirely compatible with the previous version and all the unit tests still pass. The only difference is that the method we expose (call) returns a value and is declared on Task instead of TaskBase. Also, the updateValue is only on Task.
> ObservableListTask also extends TaskBase, and adds:
>    protected abstract void call() throws Exception;    
>    protected void publish(E... items);
>    protected void publish(Collection<E> items);
> I just used the SwingWorker name "publish", but there is no process. Whatever you publish gets added. We could add a process with a default implementation if we wanted to (allowing some users to filter results or whatnot, but I'm not sure there is a reason you want to do that on the FX thread instead of the background thread, so I would propose leaving it off for now).
> This call() method returns no value, just the way it should be. You just call publish to put add items. Since the Task is a one-shot deal, there isn't really a compelling reason to add other methods like clear() (you could also do your own runLater() if you needed to do something tricky).
> What do you think? Here is an example of usage (complete with fading rectangles :-)):
>        ObservableListTask<Rectangle> task = new ObservableListTask<Rectangle>() {
>            @Override
>            protected void call() throws Exception {
>                for (int i=0; i<900; i++) {
>                    Rectangle r = new Rectangle(10, 10);
>                    r.setFill(Color.color(Math.random(), Math.random(), Math.random()));
>                    r.setOpacity(0);
>                    FadeTransition tx = new FadeTransition(Duration.seconds(1));
>                    tx.setToValue(1.0);
>                    tx.setNode(r);
>          ;
>                    publish(r);
>                    Thread.sleep(20);
>                    updateProgress(i, 900);
>                }
>            }
>        };
> Richard

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