Thermometer.kt

class Thermometer {
    var support : PropertyChangeSupport = PropertyChangeSupport(this)

    var temperature : Int = 0

    set(value) {
        support.firePropertyChange("temperature", temperature, value);
        field = value
    }

    fun addPropertyChangeListener(pcl: PropertyChangeListener?) {
        support.addPropertyChangeListener(pcl)
    }

    fun removePropertyChangeListener(pcl: PropertyChangeListener?) {
        support.removePropertyChangeListener(pcl)
    }
}