Demo.kt

class Demo{
    fun doSth(){
        val motor = ElectricMotor()
        val thermometer = Thermometer()

        thermometer.addPropertyChangeListener(motor)

        thermometer.temperature = 10
        thermometer.temperature = 50
        thermometer.temperature = 200

        thermometer.removePropertyChangeListener(motor)

        thermometer.temperature = 10
        thermometer.temperature = 50
        thermometer.temperature = 200
    }
}