A class is a type of object that represents a collection of attributes and methods. A class can correspond to multiple objects, and objects define their interaction with the outside world through their public methods, forming interfaces for interacting with the outside world.
Classes, Objects, and Interfaces#
1. Classes and Objects#
Differences:
- An object is an instance of a class. For example, a person has specific attributes such as height, weight, and name, as well as behaviors like running and dancing.
- A class is an abstract concept that represents a template for a category of things. It describes the behaviors and states of a class of objects, abstracting their commonalities to form a class.
Relationship:
- A class is a description of a thing, while an object is a specific instance that exists.
A class is a type of object that represents a collection of attributes and methods. A class can correspond to multiple objects.
2. What is an Interface?#
Objects define their interaction with the outside world through their public methods, forming interfaces for interacting with the outside world. Methods form the concrete implementation of this interaction.
At a deeper level, interfaces separate the definition and implementation, abstracting the concrete implementation of interaction.
An interface is the foundation of object-oriented programming. It is a data structure that includes function methods, and it is more abstract than a class.
It can be said that a class is the abstraction of an object, and an interface is the abstraction of a class.
For example, in daily life, a remote control acts as an interface. People use it to switch between different channels and signals, as it collects and encapsulates information of different types and converts them into information that the TV can recognize.
In programming languages, an interface is actually the encapsulation of different classes and provides a unified external communication channel, allowing other objects to call members of different classes using the interface.
Interfaces and classes are essentially the same data structure.
In an interface, properties, methods, events, and types can be declared, but variables cannot be declared. In other words, interfaces can only define members, not assign values to members.
The benefits of using interfaces are to improve code flexibility and reduce coupling between objects, which is very useful in practical projects.