带有Task的Java中的多线程仅在onClick Button上起作用一次

Question

Attached is the code snippet below. I am new to multi-threading. Attempted to do multi threading which sort of works. However, after I click the button the first time, the second time onwards would not "create the thread" and run my method anymore.

I have also experimented with implementing the Runnable interface, but it could not get my Anchorpane reference to load the snackbar and hence I used the task method instead. Appreciate your help!

    @FXML
    private AnchorPane anchorPane;

    Thread thread;
    @FXML
    void onClickLoginButton(ActionEvent event) throws Exception {
            thread = new Thread(task);
            thread.start();
    }
    Task<Void> task = new Task<Void>() {
        @Override
        public Void call(){
            //System.out.println("Thread running"+thread.getId());
            try {
                credential = login.login();
            } catch (UnknownHostException u) {
                Platform.runLater(() -> {
                    System.out.println("No wifi");
                    JFXSnackbar snackbar = new JFXSnackbar(anchorPane);
                    snackbar.show("Please check your internet connection", 3000);
                    //u.printStackTrace();
                });
            } catch (Exception e) {
                //e.printStackTrace();
            }
            //System.out.println("Thread running"+thread.getId());
            return null;
        }
    };

Answer 1

The reason why this runs only once has to do with how Task works in general

Per Task 's documentation here: https://docs.oracle.com/javase/8/javafx/api/javafx/concurrent/Task.html

As with FutureTask, a Task is a one-shot class and cannot be reused. See Service for a reusable Worker.

Thus, if you want to repeat the said process multiple times, using a Task is not a good choice. Check the recommended alternatives for workers and services in you want to achieve something like that.