Stop threads before close my JavaFX program

Question

I'm having a problem with closing my application because some threads are still running after I close the application. Somebody can help me with some method to stop all Threads being executed in background before killing the main thread???

[EDITED]

With my questions about javafx I have noticed that many newer developers are facing problem managing Threads. I would like to share what I have done to simplify my life about managing threads on javafx. I've created an AsyncTask class based on AsyncTask from Android that basically do the same of Android's in a humble but effective way. You can find more information about it on Github project

Answer 1

Better way to fix this is add the EventHandler on Close Request:

@Override
public void start(Stage primaryStage) {
    primaryStage.setOnCloseRequest(new EventHandler<WindowEvent>() {
       @Override
       public void handle(WindowEvent e) {
          Platform.exit();
          System.exit(0);
       }
    });
}

Answer 2

You have three options here - the easiest is to simply create your Threads as deamons, which means that when your main program ends all deamon threads will terminate too.

Thread thread = new Thread();
thread.setDaemon(true);

Thats easiest, but the downside is that you wont get a graceful shutdown (ie the threads will stop, you wont get a chance to peform resource management etc, which may or may not be a problem for you).

The alternative is to keep a hold on the spawned threads and when your program receives the signal to close you iterate over the threads and pass in a signal of some sort to signa that they too should terminate

volatile boolean shutdown = false;

public void shutdown() {
   shutdown = true;
}

public void run() {
    while(!shutdown) { 
        ... do your work here
    }
    ... perform any cleanup work here

(Note: ignores any exception handling for clarity)

The last option is to use the Executor framework in java.util.concurrent

ExecutorService executorService = Executors.newFixedThreadPool(10);
... assign/invoke tasks etc

... at some point later your program is told to shutdown 
... shutdown in executor too 
executorService.shutdown();
executorService.awaitTermination(10, TimeUnit.SECONDS); // wait for 10s in this case
executorService.shutdownNow();

Answer 3

Override your Application Class

//System.exit(0) This will close all timers and threads inside the Jar application...
@Override
public void stop() throws Exception {
    super.stop(); //To change body of generated methods, choose Tools | Templates.
    System.exit(0);
}

Answer 4

Executors from the java.util.concurrent package are the way to go. Explicitly:

ExecutorService executorService = Executors.newCachedThreadPool(new ThreadFactory() {
     @Override
     public Thread newThread(Runnable runnable) {
          Thread thread = Executors.defaultThreadFactory().newThread(runnable);
          thread.setDaemon(true);
          return thread;
    }
});

Java 8 version with fixed ScheduledExecutorService

ScheduledExecutorService executorService = Executors.newScheduledThreadPool(1, r -> {
    Thread thread = Executors.defaultThreadFactory().newThread(r);
    thread.setDaemon(true);
    return thread;
});