Implements abstract javafx.concurrent.Service.createTask.

Doc from javafx.concurrent.Service.createTask.

Invoked after the Service is started on the JavaFX Application Thread. Implementations should save off any state into final variables prior to creating the Task, since accessing properties defined on the Service within the background thread code of the Task will result in exceptions. For example:

    protected Task createTask() {
        final String url = myService.getUrl();
        return new Task<String>() {
            protected String call() {
                URL u = new URL("http://www.oracle.com");
                BufferedReader in = new BufferedReader(
                        new InputStreamReader(u.openStream()));
                String result = in.readLine();
                in.close();
                return result;
            }
        }
    }

If the Task is a pre-defined class (as opposed to being an anonymous class), and if it followed the recommended best-practice, then there is no need to save off state prior to constructing the Task since its state is completely provided in its constructor.

protected Task createTask() {
        // This is safe because getUrl is called on the FX Application
        // Thread and the FirstLineReaderTasks stores it as an
        // immutable property
        return new FirstLineReaderTask(myService.getUrl());
    }

Annotations

@Override

Implements abstract javafx.concurrent.Task.call.

Doc from javafx.concurrent.Task.call.

Invoked when the Task is executed, the call method must be overridden and implemented by subclasses. The call method actually performs the background thread logic. Only the updateProgress, updateMessage, updateValue and updateTitle methods of Task may be called from code within this method. Any other interaction with the Task from the background thread will result in runtime exceptions.

Annotations

@Override

Exceptions

Exception:

an unhandled exception which occurred during the background operation