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采用接口方式：

package te4;//通知接口public interface Subject {
   public void Add(BaseObserverObj obj);public void Del(BaseObserverObj obj);public void Noti();}import java.util.ArrayList;//通知类public class SubjectObj implements Subject {
       private ArrayList
   
     observers = new ArrayList
    
     ();@Override//注册到通知类中public void Add(BaseObserverObj obj) {    // TODO Auto-generated method stub    observers.add(obj);}//删除@Override    public void Del(BaseObserverObj obj) {        // TODO Auto-generated method stub        observers.remove(obj);    }@Override//进行通知    public void Noti() {        // TODO Auto-generated method stub        for (BaseObserverObj obj : observers) {            obj.func();        }    }}
    
   

//观察者类，只需要继承BaseObserverObj重写func方法public class BaseObserverObj {
   protected String name;public BaseObserverObj(String name) {    // TODO Auto-generated constructor stub    this.name = name;}public void func() {    System.out.println(name+"哈哈");}}public class ObserverObj1 extends BaseObserverObj {
   public ObserverObj1(String name) {    // TODO Auto-generated constructor stubsuper(name);}@Override    public void func() {        // TODO Auto-generated method stub        System.out.println(name+"呵呵");    }}

//测试public static void main(String[] args) {        // TODO Auto-generated method stub        BaseObserverObj base1 = new BaseObserverObj("Tom");        ObserverObj1 obse1 = new ObserverObj1("BOB");        SubjectObj subobj = new SubjectObj();        subobj.Add(base1);        subobj.Add(obse1);        subobj.Noti();    }

通过静态方法实现：

mport java.util.ArrayList;import org.omg.CosNaming.NamingContextExtPackage.AddressHelper;//通知类public  class Boss {static ArrayList
   
     emploees = new ArrayList
    
     ();public  static void Add(employee em){    emploees.add(em);}public static void Del(employee em){    emploees.remove(em);}public static void Noti(){    for (employee emp :emploees) {        emp.func();    }}}
    
   

//观察者类,继承employee实现抽象函数func即可public abstract class employee {
       protected String name;    public employee(String nameString) {        // TODO Auto-generated constructor stub    name = nameString;    }public abstract void func();}package te3;public class employee1 extends employee{
   public employee1(String nameString) {    // TODO Auto-generated constructor stubsuper(nameString);}@Overridepublic void func() {    // TODO Auto-generated method stub    System.out.println(name+"干活了,别打游戏了");}}public class employee2 extends employee {
   public employee2(String name) {    // TODO Auto-generated constructor stub    super(name);}@Overridepublic void func() {    // TODO Auto-generated method stubSystem.out.println(name+"工作了,别斗地主了");   }}

//测试Boss.Noti();    employee1 emp1 = new employee1("BOB");    employee2 emp2 = new employee2("John");    Boss.Add(emp1);    Boss.Add(emp2);    Boss.Noti();    Boss.Del(emp1);    Boss.Add(new employee1("Tom"));    employee emp3 = new employee("Merry") {        @Override        public void func() {            // TODO Auto-generated method stub            System.out.println(name +"上班了，别斗地主了");        }    };    Boss.Add(emp3);    Boss.Noti();}

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