封装和抽象之间的确切区别是什么?
当前回答
封装要求模块化。它要求您创建具有数据和处理数据的方法的对象。在这种情况下，您可以将其视为一个模块。
抽象为您提供了类的一般视图。
其他回答
这里的大多数答案都关注于OOP，但封装开始得更早:
Every function is an encapsulation; in pseudocode: point x = { 1, 4 } point y = { 23, 42 } numeric d = distance(x, y) Here, distance encapsulates the calculation of the (Euclidean) distance between two points in a plane: it hides implementation details. This is encapsulation, pure and simple. Abstraction is the process of generalisation: taking a concrete implementation and making it applicable to different, albeit somewhat related, types of data. The classical example of abstraction is C’s qsort function to sort data: The thing about qsort is that it doesn't care about the data it sorts — in fact, it doesn’t know what data it sorts. Rather, its input type is a typeless pointer (void*) which is just C’s way of saying “I don't care about the type of data” (this is also called type erasure). The important point is that the implementation of qsort always stays the same, regardless of data type. The only thing that has to change is the compare function, which differs from data type to data type. qsort therefore expects the user to provide said compare function as a function argument.
封装和抽象是密切相关的，因此您可以认为它们确实是不可分割的。就实际而言，这可能是对的;也就是说，这里有一个不太抽象的封装:
class point {
numeric x
numeric y
}
我们封装了点的坐标，但是我们没有实质性地将它们抽象出来，只是在逻辑上对它们进行分组。
这里有一个抽象的例子，它不是封装:
T pi<T> = 3.1415926535
这是一个具有给定值(π)的泛型变量pi，声明并不关心变量的确切类型。诚然，我很难在真实的代码中找到这样的东西:抽象实际上总是使用封装。然而，上面的内容在c++(14)中确实存在，通过变量模板(=变量的通用模板);使用稍微复杂一点的语法，例如:
template <typename T> constexpr T pi = T{3.1415926535};
抽象是广义的术语。即封装是抽象的子集。
| Abstraction | Encapsulation |
|---|---|
| It solves an issue at the design level. | Encapsulation solves an issue at implementation level. |
| hides the unnecessary detail but shows the essential information. | It hides the code and data into a single entity or unit so that the data can be protected from the outside world. |
| Focuses on the external lookout. | Focuses on internal working. |
| Lets focus on what an object does instead of how it does it. | Lets focus on how an object does something. |
| Example: Outer look of mobile, like it has a display screen and buttons. | Example: Inner details of mobile, how button and display screen connect with each other using circuits. |
示例:解决方案架构师是创建整个解决方案的高级抽象技术设计的人，然后将该设计移交给开发团队进行实现。 在这里，解决方案架构师充当抽象，而开发团队充当封装。
举例:用户数据的封装(组网)
图片由
Abstraction (or modularity) – Types enable programmers to think at a higher level than the bit or byte, not bothering with low-level implementation. For example, programmers can begin to think of a string as a set of character values instead of as a mere array of bytes. Higher still, types enable programmers to think about and express interfaces between two of any-sized subsystems. This enables more levels of localization so that the definitions required for interoperability of the subsystems remain consistent when those two subsystems communicate. Source
Java示例
封装要求模块化。它要求您创建具有数据和处理数据的方法的对象。在这种情况下，您可以将其视为一个模块。
抽象为您提供了类的一般视图。
抽象和封装过程都会生成接口。
通过封装生成的接口隐藏了实现细节。
与抽象之前相比，通过抽象生成的接口可以适用于更多的数据类型。
抽象和封装的区别。
