Detect that a javaFX/TornadoFX application has not been used

For KeepassFX I needed a way to close the UI when the UI has not been used for a certain amount of time (15 minutes by default) This turned out to be much easier then I thought as I only have one stage to keep track off:

First in the App.kt override the start method:

override fun start(stage: Stage) {
    super.start(stage)
    idleTimer = fixedRateTimer(name = "idle-timer", period = 1000) {
        if (!FX.primaryStage.isIconified && System.currentTimeMillis() > (idleTime + 1000)) {
            println("lock screen!")
        }
    }
    stage.addEventFilter(InputEvent.ANY) {
        updateTimer()
    }
}

This creates a timer that will run every second and check if the idletime is older then current time minus 1 second(this is a proof of concept :) ) It will print lock screen! if so.

It also sets a filter on any type of input (keyboard or mouse) that will update the idleTime if an event has occurred. The updateTimer is very simple:

private fun updateTimer() {
    idleTime = System.currentTimeMillis()
}

Done.

Don’t forget to stop the Timer when you end the program:

override fun stop() {
    idleTimer.cancel()
}