I have a stream

Thread skillshowin = new Thread(new Runnable() {
    @Override
    public void run() {
        try {
            newskill.setStyle("visibility: true");
            Thread.sleep(10000);
            Thread.interrupted();
        } catch (Exception e) {
            skill.setText("" + Integer.valueOf(skill.getText()) + 5);
            newskill.setStyle("visibility: false");
        }
    }
});
skillshowin.start();

But I get the error Exception in thread "Thread-5" java.lang.IllegalStateException: Not on FX application thread; currentThread = Thread-5when executing skill.setText

Answer 1, authority 100%

To modify UIin other threads in JavaFX, you must use other means:

Platform.runLater():

Option with lambda:

Platform.runLater(() -> {
    //your code
});

Alternatively with Runnable:

Platform.runLater(new Runnable() {
    @Override
    public void run() {
        //your code
    }
});

As well as Serviceand Task. The Serviceis more powerful than the normal Thread. Changing UIinside Taskwill not throw out Not on FX application thread, but inside Taskyou also need to write Platform.runLater(), otherwise all sorts of errors may occur.

Service service = new Service() {
    @Override
    protected Task createTask() {
        return new Task() {
            @Override
            protected Object call() throws Exception {
                Platform.runLater(() -> {
                    //your code
                });
                return null;
            }
        };
    }
};
service.start();