Java built-in observer pattern sample

Displayelement.java

 Public Interface displayelement {publicvoid  display ();}

Currentconditionsdisplay.java

ImportJava.util.Observer;Importjava.util.Observable; Public classCurrentconditionsdisplayImplementsObserver, displayelement {Observable Observable; Private floattemperature; Private floathumidity;  PublicCurrentconditionsdisplay (Observable Observable) { This. observable =observable; Observable.addobserver ( This); }         Public voidUpdate (Observable obs, Object Arg) {if(Obsinstanceofweatherdata) {Weatherdata Weatherdata=(Weatherdata) Obs;  This. Temperature =weatherdata.gettemperature ();  This. Humidity =weatherdata.gethumidity ();        Display (); }            }         Public voiddisplay () {System.out.println ("Current coditions:" +Temperature+ "F degress and" + humidity + "% humidity"); }    }

Weatherdata.java

Importjava.util.Observable; Public classWeatherdataextendsObservable {Private floattemperature; Private floathumidity; Private floatpressure;  PublicWeatherdata () {} Public voidmeasurementschanged () {setchanged ();    Notifyobservers (); }         Public voidSetmeasurements (floatTemperature,floatHumidity,floatpressure) {         This. Temperature =temperature;  This. Humidity =humidity;  This. Pressure =pressure;    Measurementschanged (); }         Public floatgettemperature () {returntemperature; }     Public floatgethumidity () {returnhumidity; }     Public floatgetpressure () {returnpressure; }    }

Weatherstation.java

 Public classweatherstation { Public Static voidMain (string[] args) {//TODO auto-generated Method StubWeatherdata Weatherdata =NewWeatherdata (); Currentconditionsdisplay Currentdisplay=NewCurrentconditionsdisplay (Weatherdata); //Statisticsdisplay statisticsdisplay = new Statisticsdisplay (weatherdata); //Forecastdisplay forecastdisplay = new Forcecastdisplay (weatherdata);weatherdata.setmeasurements (30.4f); Weatherdata.setmeasurements (29.4f, the); Weatherdata.setmeasurements (29.4f); }}

Java built-in observer pattern sample