package com.vince.observer;
public interface Observable {
//注册为一个观察者
public void registerObserver(Observer observer);
//取消观察者
public void removeObserver(Observer observer);
//通知所有观察者更新信息
public void notifyObservers();
}
package com.vince.observer;
public interface Observable {
//注册为一个观察者
public void registerObserver(Observer observer);
//取消观察者
public void removeObserver(Observer observer);
//通知所有观察者更新信息
public void notifyObservers();
}
package com.vince.observer;
public interface Observer {
public void update(float price);
}
package com.vince.observer;
public class Person implements Observer{
private String name;
public Person(String name){
this.name = name;
}
@Override
public void update(float price) {
System.out.println(name+"关注的杯子的价格已更新为:"+price);
}
}
package com.vince.observer;
public class Test {
public static void main(String[] args) {
//创建一个被观察者对象
Cup doll = new Cup(3000);
//创建两个观察者对象
Person p1 = new Person("生命壹号");
Person p2 = new Person("生命贰号");
//注册成为一个观察者
doll.registerObserver(p1);
doll.registerObserver(p2);
System.out.println("第一轮促销:");
doll.setPrice(2698);// 价格变动
System.out.println("第二轮促销:");
doll.setPrice(2299);//
System.out.println("第三轮促销:");
doll.setPrice(1998);
doll.removeObserver(p2); //将生命二号移除
System.out.println("第四轮促销:");
doll.setPrice(1098);
}
}
package com.vince.observer2;
import java.util.Observable;
public class Cup extends Observable{
private float price;
public Cup(float price){
this.price = price;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
this.setChanged();//通知,数据已改变
this.notifyObservers();
}
}
package com.vince.observer2;
import java.util.Observable;
import java.util.Observer;
public class Person implements Observer{
private String name;
public Person(String name){
this.name = name;
}
@Override
public void update(Observable o, Object arg) {
if(o instanceof Cup){
Cup cup = (Cup)o;
System.out.println(name+"关注的杯子价格已更新为:"+cup.getPrice());
}
}
}
package com.vince.observer2;
public class Test {
public static void main(String[] args) {
Cup cup = new Cup(3000);
Person p1 = new Person("生命壹号");
Person p2 = new Person("生命贰号");
cup.addObserver(p1);
cup.addObserver(p2);
System.out.println("第一轮促销");
cup.setPrice(2988);
System.out.println("第二轮促销");
cup.setPrice(2698);
cup.deleteObserver(p2);
System.out.println("第三轮促销");
cup.setPrice(1998);
}
}
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