封装和抽象之间的确切区别是什么?


当前回答

我试图在抽象和封装之间画一条线,根据我的观点,抽象更多的是概念性的东西,而封装是抽象实现的一种。因为一个人可以隐藏数据而不封装,例如使用私有常数或变量;所以我们可以用数据隐藏进行封装,但数据隐藏并不总是封装。在下面这段代码中,我试图描述这些概念的最简单形式。

    // Abstraction
    interface IOperation
    {
        int SquareNumber();
    }

    public class Operation
    {
        // Data hiding
        private int number;

        public Operation(int _number)
        {
            this.number = _number;
        }

        // Encapsulation
        public int SquareNumber()
        {
            return number * number;
        }
    }

在行动,

IOperation obj = new Operation(2); 
// obj.number  <--- can't access because hidden from world using private access modifier but not encapsulated. 
obj.SquareNumber(); // cannot access internal logic to calculate square because logic is hidden using encapsulation.

其他回答

一种防止特定对象的数据被外部函数故意或意外误用的机制叫做“数据封装”。

在不包括背景细节或解释的情况下表现基本特征的行为被称为抽象

封装是抽象的一个例子。封装的全部意义在于抽象函数内部发生的事情,将所有的复杂性简化为一个符号(函数的引用或名称),将函数变成一个黑盒。

在编程中,“抽象”一词是一个命令。当一个类继承了一个抽象类(或接口)时,您将被命令创建一个抽象。

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

下面这段话帮助我理解了它们之间的区别:

数据封装是一种捆绑数据的机制 使用它们的函数和数据抽象是一种机制 只暴露接口,隐藏实现细节 来自用户。

你可以在这里阅读更多。

上面提供了很多很好的答案,但我将在这里介绍我的(Java)观点。

数据封装简单地说就是包装和控制类中逻辑分组数据的访问。它通常与另一个关键字-数据隐藏相关联。这是在Java中使用访问修饰符实现的。

一个简单的例子是定义一个私有变量,并使用getter和setter方法访问它,或者将一个方法设置为私有,因为它只在类中使用。用户不需要知道这些方法和变量。

注意:不要误解封装只是关于数据隐藏。当我们说封装时,重点应该是将相关数据和行为分组、打包或捆绑在一起。

另一方面,数据抽象是泛化的概念,这样底层的复杂逻辑就不会暴露给用户。在Java中,这是通过使用接口和抽象类实现的。

的例子,

Lets say we have an interface Animal and it has a function makeSound(). There are two concrete classes Dog and Cat that implement this interface. These concrete classes have separate implementations of makeSound() function. Now lets say we have a animal(We get this from some external module). All user knows is that the object that it is receiving is some Animal and it is the users responsibility to print the animal sound. One brute force way is to check the object received to identify it's type, then typecast it to that Animal type and then call makeSound() on it. But a neater way is to abstracts thing out. Use Animal as a polymorphic reference and call makeSound() on it. At runtime depending on what the real Object type is proper function will be invoked.

详情请点击这里。

复杂的逻辑是在电路板中,封装在一个触摸板中,并提供了一个漂亮的界面(按钮)来将其抽象给用户。

附注:以上链接是我的个人博客。