封装和抽象之间的确切区别是什么?


当前回答

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};

其他回答

抽象是对用户隐藏无用的数据 封装是将数据绑定到一个胶囊(类)中。 我认为封装是我们实现抽象的方式。

封装隐藏了实现细节,这些细节可能是通用的,也可能不是专门的行为。

抽象提供了一种泛化(例如,在一组行为之上)。

这里有一个很好的阅读:抽象、封装和信息隐藏,作者是Object Agency的Edward V. Berard。

我将尝试以一种简单的方式演示封装。让我们看看. .

将数据和函数包装成一个单元(称为 类)被称为封装。封装、包含和隐藏 关于对象的信息,如内部数据结构和 代码。

封装是-

隐藏的复杂性, 将数据和函数绑定在一起, 使复杂方法私有, 使实例变量为私有, 对最终用户隐藏不必要的数据和函数。

封装实现了抽象。

抽象就是——

显示什么是必要的, 数据需要从最终用户,

让我们看一个例子

下图显示了“将客户详细信息添加到数据库”的图形用户界面。

通过查看图像,我们可以说我们需要一个客户类。

步骤- 1:我的客户类需要什么?

i.e.

2个变量来存储客户代码和客户名称。 1添加客户代码和客户名称到数据库功能。 名称空间CustomerContent { 公共类客户 { CustomerCode = ""; CustomerName = ""; 公共无效ADD() { //我的DB代码会在这里 }

现在只有ADD方法不会在这里单独工作。

步骤-2:验证将如何工作,ADD函数的行为?

我们将需要数据库连接代码和验证代码(额外的方法)。

public bool Validate()
{
    //Granular Customer Code and Name
    return true;
}

public bool CreateDBObject()
{
    //DB Connection Code
    return true;
}


class Program
{
static void main(String[] args)
{
CustomerComponent.Customer obj = new CustomerComponent.Customer;

obj.CustomerCode = "s001";
obj.CustomerName = "Mac";

obj.Validate();
obj.CreateDBObject();

obj.ADD();
}
}

现在不需要显示额外的方法(Validate();CreateDBObject()[复杂和额外的方法])给最终用户。最终用户只需要看到和知道客户代码,客户名称和ADD按钮,这将添加记录。最终用户不关心如何将数据添加到数据库?

步骤-3:私有不涉及最终用户交互的额外和复杂的方法。

所以使那些复杂的和额外的方法为私有而不是公共(i。e隐藏这些方法),并删除obj.Validate();obj.CreateDBObject ();从主类程序中实现封装。

换句话说,将接口简化为终端用户就是封装。

现在代码如下所示

namespace CustomerContent
{
public class Customer
{
public string CustomerCode = "";
public string CustomerName = "";
public void ADD()
{
   //my DB code will go here
}

private bool Validate()
{
    //Granular Customer Code and Name
    return true;
}

private bool CreateDBObject()
{
    //DB Connection Code
    return true;
}


class Program
{
static void main(String[] args)
{
CustomerComponent.Customer obj = new CustomerComponent.Customer;

obj.CustomerCode = "s001";

obj.CustomerName = "Mac";

obj.ADD();
}
}

简介:

步骤-1:我的客户类需要什么?是抽象的。

步骤-3:封装不涉及最终用户交互的额外和复杂的方法。

附注:上面的代码是硬而快速的。

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};

封装是将复杂性包裹在一个胶囊中,即类&因此封装… 抽象是一个对象区别于其他对象的特征。

抽象可以通过使具有一个或多个抽象方法的类抽象来实现。它只是一个特性,应该由扩展它的类来实现。 例如,当你发明/设计一辆汽车时,你定义了一个特征,比如汽车应该有4个门、刹车、方向盘等,所以任何使用这种设计的人都应该包括这些特征。实现并不是抽象的首要部分。它只会定义应该包含的特征。

Encapsulation is achieved keeping data and the behaviour in one capsule that is class & by making use of access modifiers like public, private, protected along with inheritance, aggregation or composition. So you only show only required things, that too, only to the extent you want to show. i.e. public, protected, friendly & private ka funda…… e.g. GM decides to use the abstracted design of car above. But they have various products having the same characteristics & doing almost same functionality. So they write a class which extends the above abstract class. It says how gear box should work, how break should work, how steering wheel should work. Then all the products just use this common functionality. They need not know how the gear box works or break works or steering wheal works. Indivisual product can surely have more features like a/c or auto lock etc…..

两者都很强大;但是使用抽象需要比封装更多的技能,没有抽象,更大的应用程序/产品就无法生存。