public StatisticsDisplay(Weatherdata weatherData)
 {
     this.weatherData = weatherData;
     weatherData.registerObserver(this);
 }
 public HeatIndexDisplay(Weatherdata weatherData)
 {
     this.weatherData = weatherData;
     weatherData.removeObserver(this);
 }
 public ForecastDisplay(Weatherdata weatherData)
 {
     this.weatherData = weatherData;
     weatherData.registerObserver(this);
 }