[Android][Kotlin] Press the back key twice to exit

    // Property that stores the button press time
    var initTime = 0L

    // Back button event handler
    override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
        // Processing when the back button is pressed
        if (keyCode === KeyEvent.KEYCODE_BACK) {
            // Handles when the back button is pressed for the first time or when 3 seconds have passed since the back button was pressed
            if (System.currentTimeMillis() - initTime > 3000) {
                Toast.makeText(this, "Press again to exit", Toast.LENGTH_SHORT).show()
                initTime = System.currentTimeMillis()
                return true
            }
        }
        return super.onKeyDown(keyCode, event)
    }