抽象类与接口 [英] Abstract Class vs. Interface

问题描述

我搜索了SO以及其他网页以获得一个好的答案，但我找不到一个我真正理解的内容。我将以不同的方式呈现这一点，并希望答案也能帮助其他人。

I have searched around SO as well as the rest of the web for a good answer but I have't found one that I really understand. I am going to present this in a different way and hopefully the answers will help others as well.

据我所知，这两个概念具有相同的规则，但由于方法实现能力，抽象类更灵活。另外，我知道你可以实现多个接口，只扩展一个类，但我确信与我提到的两个接口有更多不同。

As far as I understand, the two concepts have the same rules except an abstract class is more flexible due to the method implementation ability. Also, I am aware you can implement multiple interfaces and only extend a single class but I'm sure there are more differences than the two I mentioned.

请看一下两个代码段，给我一个例子，我可以用我的每个例子来做我想要或不想使用另一个。

Please look at the two snippets of code and give me an example what I can do with each of my examples that would make me want or not want to use the other.

abstract class Foo {
    abstract public function getValue();
    abstract public function setValue($value); 
}


class myObj extends Foo {
    function getValue() {

    }
    function setValue($value) {

    }
}

接口

Interface

interface Foo {
    public function getValue();
    public function setValue($value);
}

class myObj implements Foo {
    function getValue() {

    }
    function setValue($value) {

    }
}

推荐答案

要恢复这个想法（全球，不详细）：

To resume the idea (globally, not in detail):

inheritance

是从扩展的概念，并可选择添加一些新功能或覆盖某些现有功能（至做不同的）。但是使用继承，您可以与父代共享大部分代码。 您父母+其他一些事情。

is the notion to extend from something, and optionally add some new feature or override some existing feature (to do differently). But using inheritance, you share a big part of code with the parent. You are a parent + some other things.

interface

表示一些能力（我们说一个类是实现一个接口，表示它具有这些能力）。接口可以由2个类实现，这两个类完全不同并且不共享它们的代码（它们实现的方法除外）。当A和B实现接口C时，A不是B而B不是A。

is representing some abilities (we says a class is implementing an interface to says that it has these abilities). An interface can be implemented by 2 classes which are completely different and do not share their code (except for methods they implements). When A and B are implementing interface C, A is not a B and B is not a A.

interface <的原因之一/ code>确实允许程序员执行与多继承相同的操作，但没有多继承问题。

And one of the reason for interface is indeed to allow programmer to do the same as they could do with multi-inheritance, but without multi-inheritance problems.

使用此概念在一些编程语言中，如JAVA，PHP ......

This notion is used in some programming languages like JAVA, PHP...

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