HeadFirst 设计模式学习笔记2--观察者模式 demo

package headfirst.demo2; import java.util.ArrayList; public class WeatherData implements Subject { private ArrayList observers; private float temperature; private float humidity; private float pressure; public WeatherData(){ observers = new ArrayList(); } @Override public void notifyObservers() { for(int i=0; i<observers.size();i++){ Observer observer = (Observer)observers.get(i); observer.update(temperature, humidity, pressure); } } @Override public void registerObserver(Observer o) { observers.add(o); } @Override public void removeObserver(Observer o) { int i=observers.indexOf(o); if(i>=0){ observers.remove(i); } } public void measurementsChanged(){ notifyObservers(); } public void setMeasurements(float temperature, float humidity, float pressure){ this.temperature = temperature; this.humidity = humidity; this.pressure= pressure; measurementsChanged(); } public float getTemperature(){ return temperature; } public float getHumidity(){ return humidity; } public float getPressure(){ return pressure; } }