I read two articles in the garden and initially understood the meaning of "interface ".

Source: Internet
Author: User
Tags define abstract

Previously, the concept of "interface" was vague. I read two articles in the garden today and started to understand the following:

Http://www.cnblogs.com/AndyFish/archive/2008/08/11/1265232.html (reproduced)

Http://www.cnblogs.com/anytao/archive/2007/04/12/must_net_02.html (reproduced)

Both authors are well summarized:

(1) similarities (abstract class and interface are used to define abstract classes in C #2.0 ):


They cannot be directly instantiated. They can all be inherited to implement their abstract methods;


It is the technical basis for abstract programming and implements many design modes;


(2) differences:


Abstract class can have its own data members or non-abstarct member methods. In an interface, only static data members cannot be modified. The interface does not allow any member implementation;

['Note this difference when designing the class']


Interfaces are used to find functional differences between objects with large differences. abstract base classes are used to find functional differences between objects with large differences.

-> This is why abstract class and interface have different design concepts.

-> It can be said that abstract class represents the "is-a" relation, and interface represents ("can-do relation") (or "like-a" relation );

This difference clearly represents the essential difference between abstract class and interface, which is described as follows:


Looking at the example given by the previous author, when writing a "alarm door" class, he uses:

Code class Door
Abstract void open ();

Abstract void close ();



Code class Car

Abstract void start ();

Abstract void park ();


Interface Alarm
Void alarm ();


Class AlarmDoor: Door, Alarm


Class AlarmCar: Car, Alarm



Explanation: AlarmDoor is essentially a Door (is door), but it can implement the "alarm" function (can do alarm)

AlarmCar is essentially a Car, but can be used to generate alarms (can do alarm)


The function of the interface is also reflected here: there are great differences between the "door", "car", and "alarm" functions, the use of the "interface" makes the two well integrated, although in C ++, class inheritance can also achieve Door-> AlarmDoor and Car-> AlarmCar, however, its design philosophy is not directly clear by using "interfaces.


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