Concurrent Task/Service Exception

Question

Olá! How can I get the exception raised on a concurrent Task/Service class?
I have this Service:
private Service<Void> myService = new Service<Void>() {
    @Override
    protected Task createTask() {
        return new Task<Void>() {
            @Override
            protected Void call() throws Exception {
                throw new Exception("Hello, exception!");
};And this initialize function:
@Override
public void initialize(URL url, ResourceBundle resourceBundle) {
    myService.stateProperty().addListener(new ChangeListener<State>() {
        @Override
        public void changed(ObservableValue<? extends State> ov, State t, State t1) {
            System.out.println("state.changed " + t1);
    myService.exceptionProperty().addListener(new ChangeListener<Throwable>() {
        @Override
        public void changed(ObservableValue<? extends Throwable> ov, Throwable t, Throwable t1) {
            t1.printStackTrace();
}I call the Service this way:
@FXML
protected void myButtonAction(ActionEvent event) {
    myService.start();
}Finally, the output is:
state.changed SCHEDULED
state.changed RUNNING
And the function silently stops at the point of the exception.
There's a way to get the exception raised?
Thanks,
Victor (Brazil)
PS: b42.
Edited by: Victor on 05/09/2011 07:32

Answer 1

Hi Victor,
This is unfortunately a bug in the Asynch implementation at the moment. Seems a fix is due in b43: http://javafx-jira.kenai.com/browse/RT-15612
In the interim, I am using a dodgy little hack. I create my own Service base class like so:
private Service<Void> myService = new Service<Void>() {
    private Throwable lastException;   
    @Override
    protected Task createTask() {
        return new Task<Void>() {
            @Override
            protected Void call() throws Exception {
                lastException = null;
                try {
                    // do background task as normal
                catch (Throwable t) {
                    lastException = t;
};Then your initialise looks something like:
@Override
public void initialize(URL url, ResourceBundle resourceBundle) {
    myService.stateProperty().addListener(new ChangeListener<State>() {
        @Override
        public void changed(ObservableValue<? extends State> ov, State t, State t1) {
             if (t1 == Worker.State.SUCCEEDED) {
                 if (myService.getException() != null) {
                     // do success
                 } else {
                     // do failure with myService.getException()
}If you go for this, t's worth creating a base class that hides this cludge, then when b43 is released you have less refactoring to do.
Enjoy,
zonski