可一个类扩展两个类？ [英] Can one class extend two classes?

问题描述

我的类应该扩展两个类在同一时间：

 公共类preferences延伸AbstractBillingActivity {

公共类preferences扩展preferenceActivity {
 

怎么办呢？

UPD 。由于这是不可能的，我应该怎么使用 AbstractBillingActivity 用preferences呢？

UPD2 。如果我去的接口，应创建：

1. BillingInterface

    公共接口BillingInterface扩展preferenceActivity，AbstractBillingActivity {
   
   }
    

2. preferenceActivity

    公共接口preferenceActivity {
   
   }
    

3. AbstractBillingActivity

    公共接口AbstractBillingActivity {
   
           无效的onCreate（包savedInstanceState）;
   
   }
    

然后

 公共类preferences实现BillingInterface {
 

解决方案

Java不支持多重继承。

有几个解决方法我能想到的：

首先是聚集：做一个类，需要这两个活动领域

二是使用接口。

三是要重新考虑你的设计：是否有意义了 preferences 类既是 preferenceActivity 的和的的 AbstractBillingActivity ？

My class should extend two classes at the same time:

public class Preferences extends AbstractBillingActivity {

public class Preferences extends PreferenceActivity {

How to do so?

Upd. Since this is not possible, how should I use that AbstractBillingActivity with Preferences then?

Upd2. If I go with interfaces, should I create:

1. BillingInterface

   public interface BillingInterface extends PreferenceActivity, AbstractBillingActivity {
   
   }
   

2. PreferenceActivity

   public interface PreferenceActivity {
   
   }
   

3. AbstractBillingActivity

   public interface AbstractBillingActivity {
   
           void onCreate(Bundle savedInstanceState);
   
   }
   

and then

public class Preferences implements BillingInterface {

解决方案

Java does not support multiple inheritance.

There are a few workarounds I can think of:

The first is aggregation: make a class that takes those two activities as fields.

The second is to use interfaces.

The third is to rethink your design: does it make sense for a Preferences class to be both a PreferenceActivity and an AbstractBillingActivity?

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