java之观察者模式
import java.util.Observable;
import java.util.Observer;
class House extends Observable {
private float price;
public float getPrice() {
return price;
}
public void setPrice(float price) {
super.setChanged();
super.notifyObservers(price);
this.price = price;
}
public String toString() {
return "House [price=" + price + "]";
}
public House(float price) {
this.price = price;
}
}
class HousePriceObserver implements Observer {
private String nameString;
public HousePriceObserver(String name) {
this.nameString = name;
}
@Override
public void update(Observable o, Object arg) {
if (arg instanceof Float) {
System.out.print(this.nameString + "price changed to be: ");
System.out.println(((Float) arg).floatValue());
}
}
}
public class ObserDemo01 {
public static void main(String[] args) {
House house = new House(100000);
HousePriceObserver hPriceObserver01 = new HousePriceObserver("A");
HousePriceObserver hPriceObserver02 = new HousePriceObserver("B");
HousePriceObserver hPriceObserver03 = new HousePriceObserver("B");
house.addObserver(hPriceObserver01);
house.addObserver(hPriceObserver02);
house.addObserver(hPriceObserver03);
System.out.println(house);
house.setPrice(594030900);
System.out.println(house);
}
}
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