子类覆盖了父类中的同名方法，父类引用调用子类中覆盖了父类中同名方法，为什么会调用父类中的同名方法

Question

子类覆盖了父类中的同名方法，父类引用调用子类中覆盖了父类中同名方法，为什么会调用父类中的同名方法
public abstract class Beverage{
String description = "Unknow Beverage"；
public String getDescription(){
return "Unknow Beverage"；
}
public abstract double cost();
}

public abstract class CondimentDecorator extends Beverage{
public abstract String getDescription();
}

public class Espresso extends Beverage{
public Espresso(){
description = "Espresso";
}
public double cost(){
return 1.99;
}
}

public class HouseBlend extends Beverage{
public HouseBlend(){
description = "House Blend Coffee";
}
public double cost(){
return 1;
}
}

public class DarkRoast extends Beverage{
public DarkRoast(){
description = "Dark Roast Coffee";
}
public double cost(){
return 1.2;
}
}

public class Mocha extends CondimentDecorator{
Beverage beverage;
public Mocha(Beverage beverage){
this.beverage = beverage;
}
public String getDescription{
return beverage.getDescription+",Mocha";
}
public double cost(){
return 0.2+beverage.cost();
}
}

public class Whip extends CondimentDecorator{
Beverage beverage;
public Whip(Beverage beverage){
this.beverage = beverage;
}
public String getDescription{
return beverage.getDescription+",Whip";
}
public double cost(){
return 0.9+beverage.cost();
}
}

public class StarbuzzCoffee{
public static void main(String args[]){
Beverage beverage =new Espresso();
System.out.println(beverage.getDescription()+"$"+beverage.cost());
Beverage beverage2 = new DarkRoast();
beverage2 = new Mocha(beverage2);
beverage2 = new Mocha(beverage2);
beverage2 = new Whip(beverage2);
System.out.println(beverage2.getDescription()+"$"+beverage2.cost());
}
}

调用getDescription（）的时候为什么只显示，抽象类中的Unkunw Beverage？？？为什么没有被装饰？？我很奇怪

Answer 1

呵呵，你的基类Beverage的getDescription()方法是写死的返回Unkunw Beverage，又不是返回了属性description的值，所以直接继承Beverage的Espresso和DarkRoast的getDescription()方法理所当然返回Unkunw Beverage，无论description属性的值是什么，至于CondimentDecorator类虽然覆盖了getDescription()方法，但是还有用了DarkRoast作为第一个传进来的Beverage类，所以还是显示了Unkunw Beverage，只不过最后多了点后缀而已