天乙贵人

public abstract class Factory { public abstract Car createCar(); } 、、、、、、、、、、、、、、、、、、、、、、、、、、、 public class AodiFactory extends Factory{ public Car createCar(){ return new Aodi(); } } public class BencFactory ex

public abstract class Node { public abstract int getLength(); } public class Directory extends Node{ private List list; public Directory(){ list=new ArrayList(); } @Override public int getLength() { int sum=0;

public abstract class Element { public abstract double getValue(); } public class Expression extends Element{ private Element e1; private Element e2; private char operator; public Expression(Element e1, Element e2,

public interface Observer { public void update(Product pro); } public class MailObserver implements Observer{ public void update(Product pro) { System.out.println("向所有会员发送邮件"+pro.getName()+"价格已经变为"+pro.getPrice()); } }

public class ConnectionPool { private static ConnectionPool pool=new ConnectionPool(); //构造方法私有了 private ConnectionPool(){ } public static ConnectionPool getPool(){ return pool; } } //反射能够破怀单例，对象序列化也能破坏，对象的序列化说