为什么接口无法实现其他接口？ [英] Why an interface can not implement another interface?

问题描述

我的意思是：

interface B {...}

interface A extends B {...} // allowed  

interface A implements B {...} // not allowed

我用谷歌搜索了它，我找到了这个：

I googled it and I found this:

implements 表示定义接口方法的实现。但是接口没有实现，所以这是不可能的。

implements denotes defining an implementation for the methods of an interface. However interfaces have no implementation so that's not possible.

但是，接口是100％抽象类，抽象类可以实现接口（100％抽象类）没有实现其方法。定义为界面时有什么问题？

However, interface is an 100% abstract class, and an abstract class can implement interfaces (100% abstract class) without implement its methods. What is the problem when it is defining as "interface" ?

详细信息，

interface A {
    void methodA();
}

abstract class B implements A {} // we may not implement methodA() but allowed

class C extends B {
   void methodA(){}
} 

interface B implements A {} // not allowed. 
//however, interface B = %100 abstract class B

推荐答案

implements 表示实现，当 interface 意图声明只提供时接口不用于实现。

implements means implementation, when interface is meant to declare just to provide interface not for implementation.

100％抽象类在功能上等同于 interface 但如果你愿意，它也可以实现（在这种情况下，它不会保持100％ abstract ），所以从JVM的角度来看，它们是不同的东西。

A 100% abstract class is functionally equivalent to an interface but it can also have implementation if you wish (in this case it won't remain 100% abstract), so from the JVM's perspective they are different things.

此外，100％抽象类中的成员变量可以具有任何访问限定符，其中在接口中它们隐式地 public static final 。

Also the member variable in a 100% abstract class can have any access qualifier, where in an interface they are implicitly public static final.

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