How to work with GUI in one thread?

Question

Java

I'm using global keyboard capture. I can not start from the thread, the simplest, changing the text on the button.

@Override
    public void nativeKeyReleased(NativeKeyEvent nativeKeyEvent) {
        Platform.runLater( () -> {
            if(nativeKeyEvent.getKeyCode() == NativeKeyEvent.VC_F2){
 //161               
Platform.runLater( () -> b_OpenNew.setText("2"));
            }
        });
    }

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at sample.Main.lambda$null$1(Main.java:163)

Answer 1

Called nativeKeyPressed methods outside of start.

Answer 2

First, look at what exactly you have null. There are 2 options, either this is nativeKeyEvent, or b_OpenNew