Java的多重继承的设计模式？ [英] Java multiple inheritance design pattern?
问题描述
我有这样的结构：
1级
Class1
的Class2 Class1的延伸
Class2 extends Class1
我有实用类上采取了Class2中做各种工作，一边一堆。
I have a pile of utility classes on the side that take a Class2 to do all kinds of work.
问题：我需要创建扩展Class2中使用这些班在Class3。在Class3将有一个谷歌API的Android的MapView。 MapViews只能从一个类扩展MapActivity创建。我需要
The problem: I need to create a Class3 extending Class2 to use those classes. Class3 will have a Google API's Android MapView. MapViews can ONLY be created FROM A CLASS EXTENDING MapActivity. I would need
在Class3扩展的Class2和MapActivity。
不能进行。
更改我的3类只延长MapActivity会要求我修改code从previous开发商囤积继承（没有双关语意）。
Changing my class3 to only extend MapActivity would require me to modify a hoard of code inherited (no pun intended) from previous developers.
更改我的CLASS3因为地图需要MapActivity只延长Class2中休息。
Changing my class3 to only extend Class2 breaks because the map requires a MapActivity.
什么是最好的办法？
编辑：一些人所说的接口解决方案。听起来像是正确的解决方案。我忘了提，虽然，Class2中是一个的摘要的类，它会来回移动实现的方法有疼痛感。很多code重复......那张干湿在这一个...：）
Several people mentioned the 'interface solution'. Sounds like the right solution. I forgot to mention, though, that Class2 is an abstract class, and it will be a pain to move the implemented methods around. A lot of code repetition... DRY goes wet on this one... :)
推荐答案
由于Java不支持多重继承，你需要周围的工作。如果我是你，我会作出这样的定义了所有你需要的东西，然后就扩展接口的 1级
Since Java does not support multiple inheritance, you need to make a work around. If I was you I would make an interface that defines all of the things you need and then just extend your Class1
或
您可以简单地让 1级延长 MapActivity ，除非它已经扩展了别的东西，但是你真的只是想这样做，如果类2 应延伸 MapActivity 。你的类2 可以延长 1级和您的在Class3 可以延长 1级和 1级可以延长 MapActivity 。
You could simply make Class1 extend MapActivity unless it already extends something else, but you would really only want to do this if Class2 should extend MapActivity. Your Class2 could extend Class1 and your Class3 could extend Class1 and Class1 could extend MapActivity.
希望这有助于！
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