JavaFX: Load data task to combine with progress bar

Question

For my JavaFX application I'd like to implement a load Task, to combine it with a progress bar.

I have a Presentation Model which looks like this:

public class PresentationModel {

    private final ObservableList<Country> countries = FXCollections.observableArrayList();
    // Wrap the ObservableList in a FilteredList (initially display all data)
    private final FilteredList<Country> filteredCountries = new FilteredList<>(countries, c -> true);
    // Wrap the FilteredList in a SortedList (because FilteredList is unmodifiable)
    private final SortedList<Country> sortedCountries = new SortedList<>(filteredCountries);

    private Task<ObservableList<Country>> task = new LoadTask();

    public PresentationModel() {
        new Thread(task).start();
    }
}

And a Task which loads the data:

public class LoadTask extends Task<ObservableList<Country>> {

    @Override
    protected ObservableList<Country> call() throws Exception {
        for (int i = 0; i < 1000; i++) {
            updateProgress(i, 1000);
            Thread.sleep(5);
        }

        ObservableList<Country> countries = FXCollections.observableArrayList();
        countries.addAll(readFromFile());

        return countries;
    }
}

This allows me to bind the ProgressIndicator pi to the progress property of the task:

pi.progressProperty().bind(model.getTask().progressProperty());

Now I need to have the loaded data from the task in the presentation model so that I can add the elements to a table: table = new TableView<>(model.getSortedCountries());

How can I access the data in the presentation model from the load task?

Answer 1

Task has onSucceeded handler called when the task succeeds. The value property has the instance returned by call method.

task.setOnSucceeded(event -> {
    ObservableList<Country> countries = (ObservableList<Country>)event.getSource().getValue();
    // do something
});

Task also has OnFailed handler called when Exception was thrown in its call method. You can handle exceptions here. (or catch all exceptions in call method.)

task.setOnFailed(event -> {
    Throwable e = event.getSource().getException();
    if (e instanceof IOException) {
        // handle exception here
    }
});