Important Differences Between Interface and Class

Interface

An interface in computer science is a set of commands or a contract that defines a set of methods, properties and events that a class or struct must implement. Interfaces are defined using the “interface” keyword and contain only the signatures of the members (methods, properties and events) without any implementation.

Interfaces are useful for creating flexible and extensible code, as they allow for classes to implement multiple interfaces and provide their own implementation of the members defined in the interfaces. This allows for a class to have multiple behaviors or functionality.

Interfaces are used in many programming languages such as Java, C#, Python, and C++. They provide a way to define a common set of methods that multiple classes can implement. This allows for different classes to be used interchangeably in a program because they all implement the same interface.

In addition to classes and structs, interfaces can also be used with other types such as objects and arrays.

Interfaces can also be used to define events and properties. For example, an interface called “ISetVolume” might define an event called “VolumeChanged” and a property called “Volume”.

Class

A class in computer science is a blueprint for creating objects (also known as instances), which are instances of the class. A class defines a set of properties (also known as attributes) and methods (also known as functions) that the objects created from the class will have.

Classes are used in object-oriented programming (OOP) to encapsulate data and behavior. Encapsulation refers to the practice of keeping the implementation details of a class hidden from the outside world and only exposing a public interface. This allows for the implementation of a class to change without affecting code that uses the class.

Classes are defined using the “class” keyword in many programming languages such as Java, C#, Python, and C++. Once a class is defined, it can be used to create objects, which are instances of the class. These objects can have their own unique properties and can call the methods defined in the class.

Inheritance is a feature in OOP that allows a class to inherit properties and methods from a parent class. This allows for the creation of a class hierarchy, where a child class can inherit properties and methods from its parent class and can also add its own properties and methods.

There are a few important differences between an interface and a class in computer science:

1. Implementation: A class provides both an implementation of methods and properties, while an interface only provides method and property signatures without any implementation.
2. Inheritance: A class can inherit from one or more classes and implement one or more interfaces, while an interface can inherit from one or more interfaces.
3. Access modifiers: Members of a class can have access modifiers such as public, protected, private and internal, whereas members of an interface are public by default.
4. Constructors: A class can have constructors and a destructor, while an interface can’t have any constructors or destructors.
5. Properties: A class can have properties with or without implementation, while an interface can only have properties without an implementation.
6. Use case: Classes are used to define an object’s behavior and state, and provide a way to create objects, while interfaces are used to define a contract that classes must implement and provide a way to create flexible and extensible code.
7. Constant, readonly and static fields: A class can have constant, readonly, and static fields, while an interface can’t have any fields.
8. Default implementation: Classes can have default implementation of methods, but interfaces can’t have any default implementation.

In conclusion, while both interfaces and classes serve similar purposes, they are implemented and used differently in computer science. A class is a blueprint for creating objects, which are instances of the class. A class defines a set of properties and methods that the objects created from the class will have. An interface is a contract that defines a set of methods, properties, and events that a class or struct must implement. Interfaces are useful for creating flexible and extensible code, as they allow for classes to implement multiple interfaces and provide their own implementation of the members defined in the interfaces.