javafx - 暂停 JavaFX 任务使应用程序崩溃

Question

我是 JavaFX 的新手。最近我试图通过在此链接上找到的 Jewelsea 修改代码：

https://gist.github.com/jewelsea/4989970#file-promptingtaskdemo-java-L87

在上面的代码中，程序使用 dialog.showAndWait() 方法暂停了 FutureTask。我试图用其他东西暂停一个任务，所以我注释掉了 showAndWait()，并用这个代码添加了一个按钮

Platform.runLater(task);
 try {
  task.get();
 } catch(ExecutionException ee) {}
 catch(InterruptedException ie) {}

在其 .setOnAction() 中，但每次按下按钮时都会使应用程序崩溃，任何帮助将不胜感激。

public class PromptingTaskDemo extends Application {
 private static final String[] SAMPLE_TEXT =
    "MISSING Lorem ipsum dolor sit amet MISSING consectetur adipisicing elit sed do eiusmod tempor incididunt MISSING ut labore et dolore magna aliqua"
    .split(" ");


@Override public void start(Stage primaryStage) {
    Label status = new Label();
    ProgressBar progress = new ProgressBar();
    Button pauseButton = new Button("Pause");

    VBox textContainer = new VBox(10);
    textContainer.setStyle("-fx-background-color: burlywood; -fx-padding: 10;");

    LoadTextTask task = new LoadTextTask(SAMPLE_TEXT, textContainer);
    status.textProperty().bind(task.messageProperty());
    progress.progressProperty().bind(task.progressProperty());

    final Thread taskThread = new Thread(task, "label-generator");
    taskThread.setDaemon(true);

    pauseButton.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {

            Platform.runLater(task);
            try {
            task.get();
            } catch(ExecutionException ee) {}
                catch(InterruptedException ie) {}
        }
    });

    VBox layout = new VBox(10);
    layout.getChildren().addAll(status, progress, pauseButton, textContainer);
    layout.setStyle("-fx-background-color: cornsilk; -fx-padding: 10;");

    primaryStage.setScene(new Scene(layout, 300, 700));
    primaryStage.show();

    taskThread.start();

}

public static void main(String[] args) { launch(args); }
}

class LoadTextTask extends Task<Void> {
private final String[] lines;
private final Pane container;
private final IntegerProperty idx = new SimpleIntegerProperty(0);

FutureTask<String> futureTask;

LoadTextTask(final String[] lines, final Pane container) {
    this.lines = lines;
    this.container = container;
}

@Override protected Void call() throws Exception {
    try {
        updateProgress(0, lines.length);

        while (idx.get() < lines.length) {
            final Label nextLabel = new Label();
            final int curIdx = idx.get();
            updateMessage("Reading Line: " + curIdx);
            String nextText = lines[curIdx];

            if ("MISSING".equals(nextText)) {
                updateMessage("Prompting for missing text for line: " + curIdx);
                futureTask = new FutureTask(
                        new MissingTextPrompt(
                                container.getScene().getWindow()
                                )
                        );
                Platform.runLater(futureTask);
                nextText = futureTask.get();

                nextLabel.setStyle("-fx-background-color: palegreen;");
            }
            nextLabel.setText(nextText);


            Platform.runLater(
                new AddNodeLater(
                    container,
                    curIdx,
                    nextLabel
                    )
                );
            idx.set(curIdx + 1);

            updateProgress(curIdx + 1, lines.length);

            Thread.sleep(200);
        }

        updateMessage("Loading Text Completed: " + idx.get() + " lines loaded");
    } catch (Throwable t) {
        t.printStackTrace();
    }
    return null;
}

class MissingTextPrompt implements Callable<String> {
    final Window owner;
    public Button pauseButton = new Button("Pause");

    MissingTextPrompt(Window owner) {
        this.owner = owner;
    }



    @Override public String call() throws Exception {
        final Stage dialog = new Stage();
        dialog.setTitle("Enter Missin Text");
        dialog.initOwner(owner);
        dialog.initStyle(StageStyle.UTILITY);
        dialog.initModality(Modality.WINDOW_MODAL);

        final TextField textField = new TextField();
        final Button submitButton = new Button("Submit");
        submitButton.setDefaultButton(true);
        submitButton.setOnAction(new EventHandler<ActionEvent>() {
            @Override public void handle(ActionEvent t) {
                dialog.close();
            }
        });

        final VBox layout = new VBox(10);
        layout.setAlignment(Pos.CENTER_RIGHT);
        layout.setStyle("-fx-background-color: azure; -fx-padding: 10;");
        layout.getChildren().setAll(textField, submitButton);

        dialog.setScene(new Scene(layout));
        //dialog.showAndWait();

        return textField.getText();
    }
}

class AddNodeLater implements Runnable {
    final Pane container;
    final Node node;
    final int idx;

    public AddNodeLater(final Pane container, final int idx, final Node node) {
        this.container = container;
        this.node = node;
        this.idx = idx;
    }

    @Override public void run() {
        container.getChildren().add(idx, node);
    }
}
}