java泛型，如何从两个类扩展? [英] java generics, how to extend from two classes?

问题描述

我想要一个Class对象，但是我想强制使用它表示的任何类来扩展A类以及B类. 我能做

I want to have a Class object, but I want to force whatever class it represents to extend class A and also class B. I can do

<T extends ClassA & ClassB>

但是不可能从两个类都进行扩展，有没有办法做到这一点?

but it is not possible to extend from both classes, Is there a way to do this?

推荐答案

在Java中，您不能拥有从两个类扩展的类，因为它不支持多重继承.您可以拥有的是这样的:

In java you cannot have a class which extends from two classes, since it doesn't support multiple inheritance. What you can have, is something like so:

public class A
...

public class B extends A
...

public class C extends B
...

然后，在通用签名中，可以指定T必须扩展C:<T extends C>.

In your generic signature, you can then specify that T must extend C: <T extends C>.

您可以看一下 Default Methods (如果您使用的是Java 8)(本质上是在接口中声明的方法)，那么在Java中，一个类可以实现多个接口.

You could give a look at Default Methods (if you are working with Java 8), which essentially are methods declared within interfaces, and in Java, a class can implement multiple interfaces.

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