如何停止线程，以使在其上运行的任务永久停止？

Question

I have a javafx application. I programmed it such that the application starts with a progress bar that runs to completion. On completion, The window closes and a login window opens. After you sign in, the login window closes and the main window opens.

But that is not what is happening in my application.

I made a task that runs the progressbar from 0 - 100 and I made the task to run on a Thread. When the task is completed, the window closes and login window opens.

The problem I am encountering is that when I sign in using the login window, the main window opens but the login window didn't close.

I wrote a method to close the login window when the main window opens, but That didnt work.

Please what am I missing?

This is the task class

public class TaskClass implements Runnable {

    @Override
    public void run() {
        for (int i = 0; i < 100; i++) {
            try {
                progress.setProgress(i / 100.0);
                Thread.sleep(100);

            } catch (InterruptedException ex) {
                Logger.getLogger(RunningController.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                // this is the method that closes the  window on which the progress bar is running
                closed(clos);  
                // this is the method that opens the login
                windowloadwindow("/inventory/management/login/InventoryManagementlogin.fxml", "DeMak Inventory");
            }
        });
    }
}

This loads the progress bar on a thread

Thread thread;

@FXML
private JFXProgressBar progress; 

@Override
public void initialize(URL url, ResourceBundle rb) {
    progress.setProgress(0.0);
    Runnable tasks = new TaskClass();
    thread = new Thread(tasks);
    thread.start();
}

After you must have signed in using the login window, This is meant to happen

loadwindow("/inventory/management/ui/Main/main.fxml", "Deemax   Inventory");  // a method that opens the main window  

closed(closew);     // a method that closes the login window

Answer 1

In order to synchronize Platform.runLater() code and background thread code you could use the CountDownLatch Class as following:

Task<Void> task = new Task<Void>() {
            @Override
            protected Void call() throws Exception {
                CountDownLatch sync = new CountDownLatch(1);  
                Platform.runLater(()->{
                    // GUI code
                    // ...
                    // end of GUI code
                    sync.countDown();
                });
                sync.await(); // This method will wait for sync.countDown() to be executed 
                // ...
                // code here will be executed after GUI code has finished
                // ...
                return null;
            }
        };
        Thread thread = new Thread(task);
        thread.start(); 

But , instead you can solve your problem much easier like this:

Task<Void> task = new Task<Void>() {
        @Override
        protected Void call() throws Exception {
            for (int i = 0; i < 100; i++) {
                final int finalCounter = i;
                Platform.runLater(()->{
                    try {
                        progress.setProgress(finalCounter / 100.0);
                    } catch (InterruptedException e) {
                        Logger.getLogger(RunningController.class.getName()).log(Level.SEVERE, null, ex);
                    }
                });
                Thread.sleep(100);
            }
            return null;
        }
        @Override
        protected void succeeded() {
            // code here will be executed after the thread had been completed
            Platform.runLater(()->{
                new Alert(Alert.AlertType.INFORMATION, "Thread Succeeded!").show();
            });
            closed(clos);      // this is the method that closes the  window on which the progress bar is running
            loadwindow("/inventory/management/login/InventoryManagementlogin.fxml", "DeMak Inventory");     // this is the method that opens the login window
            super.succeeded();
        }
        @Override
        protected void failed() {
            Platform.runLater(()->{
                new Alert(Alert.AlertType.ERROR, "Thread Failed!").show();
            });
            super.failed();
        }
    };
    Thread thread = new Thread(task);
    thread.start();

This is my closed method

         private void closed(Node nor) {
        Stage stage = (Stage)nor.getScene().getWindow();
        stage.close();
        }

This is my node object.... It is a vbox containing an X image

  @FXML
private VBox clos;

so I pass the node to the method like this.

closed(clos);