由其他线程更新 javafx 上的列表视图

Question

I need to update a listview on javafx, i tried two solution:

1.

Task task = new Task<Void>() {
    @Override public Void call() {
        while (true){
            visitsDataList = reqController.getVisits(userBean);
                Platform.runLater(() -> {
                    observableList.clear();
                    observableList.setAll(visitsDataList);
                    listVisits.setItems(observableList);
                    listVisits.setCellFactory(List -> new CustomVisitRow());
        });
        try {
                Thread.sleep(10000);
        } catch (InterruptedException e) {
                e.printStackTrace();
        }
    }
}
};

2.

new Thread(new Runnable() {
    @Override
    public void run() {
        while (true) {
            visitsDataList = reqController.getVisits(userBean);
            Platform.runLater(() -> {
                observableList.clear();
                observableList.setAll(visitsDataList);
                listVisits.setItems(observableList);
                listVisits.setCellFactory(List -> new CustomVisitRow());});
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();}}}}).start();

but I am not convinced because I believe that too many Runnable are created. there are other solutions? which of my solutions is the best?

Answer 1

Every loop you sleep the thread for ten seconds, which means you're creating a Runnable and submitting it for execution on the JavaFX Application Thread once every ten seconds. Ten seconds is an eternity to a computer. In other words, you are not creating too many Runnable objects nor are you overwhelming the FX thread. However, there are some improvements that could be made.

1. You don't need to call ObservableList#clear() , ListView#setItems , or ListView#setCellFactory every loop. For one, setting the cell factory only needs to happen once when you first create and configure the ListView . And assuming the observableList instance has been set on the ListView before starting your Thread then calling #setAll is sufficient. That method is equivalent to calling #clear followed by #addAll .

    new Thread(() -> { while (true) { List<Visit> visits = reqController.getVisits(userBean); Platform.runLater(() -> observableList.setAll(visits)); try { Thread.sleep(10_000L); } catch (InterruptedException ex) { break; } } }).start();

2. Consider using a javafx.concurrent.ScheduledService instead.

    // ScheduledService class public class VisitRefreshService extends ScheduledService<List<Visit>> { private final ObjectProperty<User> userBean = new SimpleObjectProperty<>(this, "userBean"); private final ObjectProperty<Controller> reqController = new SimpleObjectProperty<>(this, "reqController"); // getters, setters, and property getters omitted for brevity @Override protected Task<List<Visit>> createTask() { return new Task<>() { final User user = getUserBean(); final Controller controller = getReqController(); @Override protected List<Visit> call() throws Exception { return controller.getVisits(user); } } } } // Using the ScheduledService VisitRefreshService service = new VisitRefreshService(); service.setReqController(...); service.setUserBean(...); service.setExecutor(...); // Or don't set to use the default Executor service.setPeriod(Duration.seconds(10.0)); service.setOnSucceeded(event -> observableList.setAll(service.getValue())); service.setOnFailed(event -> service.getException().printStackTrace()); service.start();