为什么Java 8中的功能接口有一个抽象方法？ [英] Why Functional Interfaces in Java 8 have one Abstract Method?

问题描述

正如我们在Java 8中所知，引入了功能接口的概念。功能接口有一个 abstract 方法，可以使用多种默认或静态方法。

As we know in Java 8, the concept of functional interfaces are introduced. A Functional Interface has one abstract method and several default or static methods are possible.

但为什么Functional接口只有一个抽象方法？
如果Interface有多个抽象方法，为什么这不是一个功能接口？

But why should a Functional interface have only one abstract method? If Interface has more then one abstract method, why is this not a Functional Interface?

推荐答案

为了方便Lambda函数，引入了功能界面，也称为单一抽象方法界面。由于lambda函数只能提供1方法的实现，因此功能接口必须只有一个抽象方法。有关详细信息，请在此处参阅。

The functional interface also known as Single Abstract Method Interface was introduced to facilitate Lambda functions. Since a lambda function can only provide the implementation for 1 method it is mandatory for the functional interface to have ONLY one abstract method. For more details refer here.

编辑 - >另外值得注意的是，功能界面可以在界面中具有默认实现。您可以在上面的链接中找到有关实施的更多详细信息。

Edit -> Also worth noting here is that, a functional interface can have a default implementation in the interface. You will find a lot more details on the implementation on the link above.

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