如何从非JavaFX线程调用JavaFX控制器并等待GUI更改完成（播放视频结束）？

Question

I have 2 classes: Controller ( JavaFX controller) and MachineController (not JavaFX thread). Sometimes MachineController sent message to Controller using method setMessage .

Method setMessage(String str) should update GUI by adding String to the List and on the Label , also if it is necessary, I shoul play the video or show Images, but i must wait for end of playing video or end of showing Image (it shows some time (for example, 3-4 seconds)).

I have used Task and Platform.runLater() . But if i use Task Images are shown only sometimes, and video wasn't played at all. If i use Platform.runLater i couldn't wait to end of playing video or shoeing image, because it start in the futere.

Controller

public void setMessage(final String str) {

    Task<Void> task = new Task<>() {
        boolean test = true;
        @Override
        protected Void call() throws Exception {
            while (test) {
                currentCommandLabel.setText(str);
                commands.add(str);
                Executable show = analyze.getExec(str);
                show.exec(pane);
                Thread.sleep(1000);
            }
            return null;
        }
    };

    Thread thread = new Thread(task);
    thread.start();
    try {
        thread.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

Executable

interface Executable {
    void exec(GridPane pane);
}

Analize

Executable getExec(String string) {
    return panel -> {
                cleanZeroCell(pane1);
                File fileImage = new File("<path to image file>");
                Image image = new Image(fileImage.toURI().toString());
                imageView.setImage(image);
                panel.add(imageView, 0, 0);
            };
}

Also I have tried to used setMessage like this:

public void setMessage(final String str) {
    Platform.runLater(() -> {
        currentCommandLabel.setText(str);
        commands.add(str);
    });
    Executable show = analyze.getExec(str);
    Platform.runLater(() -> show.exec(pane));
}

Answer 1

You can use a CountDownLatch to wait for the JavaFX application thread on a non-application thread. The following example uses a animation instead of a video or "image showing", but you could easily use the MediaPlayer.onEndOfMedia event instead of Animation.onFinished event:

private void startAnimation(Button button, CountDownLatch latch) {
    TranslateTransition animation = new TranslateTransition(Duration.seconds(2), button);
    animation.setByX(100);
    animation.setOnFinished(evt -> latch.countDown());
    animation.play();
}

@Override
public void start(Stage primaryStage) {
    Button btn = new Button("Animate");
    btn.setOnAction((ActionEvent event) -> {
        new Thread(() -> {
            try {
                // simulates some work prior to modifying the ui
                Thread.sleep(2000);
            } catch (InterruptedException ex) {
            }

            CountDownLatch latch = new CountDownLatch(1);
            // start animation on application thread
            Platform.runLater(() -> startAnimation(btn, latch));
            try {
                // wait for application thread to count down the latch
                latch.await();
                System.out.println("Done");
            } catch (InterruptedException ex) {
                ex.printStackTrace(System.err);
            }

        }).start();
    });

    StackPane root = new StackPane();
    root.getChildren().add(btn);

    Scene scene = new Scene(root, 200, 200);

    primaryStage.setScene(scene);
    primaryStage.show();
}