What is use of Interface

Question

Abstract class has abstract method and not abstract method .then what is use of interface ???

Vincent Maverick Durano · Answer

Sure. Here's a simple implementation of that. First define your interface with the Sum, Difference, Multiply and Divide methods like: public interface ICalulator { T Sum(T a, T b); T Difference(T a, T b); T Multiply(T a, T b); T Divide(T a, T b); } the "T" there is the type that the iterface will be using to do the operations for example int, decimal or whatever. Now you can then create a concrete class than implement the interface: public class Int32Calculator : ICalulator { public Int32 Sum(Int32 a, Int32 b) { return a + b; } public Int32 Difference(Int32 a, Int32 b) { return a - b; } public Int32 Multiply(Int32 a, Int32 b) { return a * b; } public Int32 Divide(Int32 a, Int32 b) { return a / b; } } and use it like this: Int32Calculator calcu = new Int32Calculator(); int sum = calcu.Sum(5, 8); int sub = calcu.Difference(5,5); int mul = calcu.Multiply(2,3); int div = calcu.Divide(10,2);

Vincent Maverick Durano · Answer

You use an interface to define a protocol of behavior that can be implemented by any class anywhere in the class hierarchy. Interfaces are useful for the following: Capturing similarities among unrelated classes without artificially forcing a class relationship. Declaring methods that one or more classes are expected to implement. Revealing an object's programming interface without revealing its class. Your question has been asked many times before so I would suggest you to do a bit of search at google to get more information and examples of interfaces.

Rafnas T P · Answer

please check the link below for more about Interface https://dzone.com/articles/c-interfaces-what-are-they-and

Rathrola Prem Kumar · Answer

Interfaces are better suited to situations in which your applications require many possibly unrelated object types to provide certain functionality. Interfaces are more flexible than base classes because you can define a single implementation that can implement multiple interfaces. Interfaces are better in situations in which you do not have to inherit implementation from a base class. Interfaces are useful when you cannot use class inheritance. For example, structures cannot inherit from classes, but they can implement interfaces. Reference: https://msdn.microsoft.com/en-us/library/3b5b8ezk(v=vs.90).aspx

Lalit Raghav · Answer

MR Vincent Maverick Durano Can you give me a another example of interface .Take simple example for calculation operation as addition ,Subtraction ,multiplication and dividation

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Vincent Maverick Durano · Answer

I'll try to draft a very simple scenario on how reusability works with interfaces and essentially polymorphism. Consider that you are tasked to create a graphic editor that allows you to draw shapes to a canvas. Shapes such as circles, square, triangle etc.. There are two possible ways to implement this. It's either using polymorphism with interfaces or without using polymorphism. Now let's create a simple method called DrawShape() that takes a canvas and a shape as the parameters. The method would look something like this: public void DrawShape(Canvas canvas, Circle circle){ circle.Draw(canvas); } public void DrawShape(Canvas canvas, Triangle triangle){ triangle.Draw(canvas); } public void DrawShape(Canvas canvas, Square square){ square.Draw(canvas); } Without polymorphism, you would need to overload that method for each shape that your editor supports. Plus, odds are that in each overloaded implementation, you are rewriting some logic that is used in every signature. So if you had to go back and modify it, you have to do that for all the overloaded signatures you have. That can lead to errors if you forgot to change one. if you look at the above implementation, you have a common pattern and that is each shape is just a drawing itself, but you wrap it in a separate method signature. This can be very hard to manage when you are going to support 10 or more shapes. With Polymorphism, you could define an interface called IDrawableShape or something similar. For example you have this interface definition public interface IDrawableShape { void Draw(Canvas canvas); } The interface above have a single method called Draw(Canvas canvas) that will draw a shape on a canvas. Now you implement that on each class that you will support drawing capabilities. For example: public void DrawShape(Canvas canvas, IDrawableShape shape) { shape.Draw(canvas) } Now you have only one method that you need to call for all your shapes. Whenever you add a shape, have it implement that interface and call this method and you are all set. There are many real-world examples out there about interfaces. Just find them at google. Few of them are: http://geeks.netindonesia.net/blogs/wely/archive/2007/03/21/Interface-And-Abstract-Class.aspx http://geeks.netindonesia.net/blogs/wely/archive/2007/03/26/A-practical-_2200_polymorphism_2200_-example.aspx

Lalit Raghav · Answer

Mr Vincent Maverick Can you give me example ??

Dipankar Biswas · Answer

hi check here... http://www.c-sharpcorner.com/UploadFile/sekarbalag/interface-best-example-in-csharp/http://www.c-sharpcorner.com/UploadFile/sekarbalag/interface-best-example-in-csharp/

Rajeesh Menoth · Answer

Hi Lalit Raghav, Abstract Class: -Abstract class provides a set of rules to implement next class -Rules will be provided through abstract methods -Abstract method does not contain any definition -While inheriting abstract class all abstract methods must be override -If a class contains at least one abstract method then it must be declared as an "Abstract Class" -Abstract classes cannot be instantiated (i.e. we cannot create objects), but a reference can be created -Reference depends on child class object's memory -Abstract classes are also called as "Partial abstract classes" -Partial abstract class may contain functions with body and functions without body -If a class contains all functions without body then it is called as "Fully Abstract Class" (Interface) Interface: -If a class contains all abstract methods then that class is known as "Interface" -Interfaces support like multiple inheritance -In interface all methods r public abstract by default -Interfaces r implementable -Interfaces can be instantiated, but a reference cannot be created

Maha · Answer

Multiple inheritances are not allowed in C#. In order to fulfill such a need Interfaces are used. class A { } class B:A (B inherits from A which is allowed in C#) { } class C : A, B (C inherits from A & B. This is multiple inheritances which is not allowed in C#) { }

Gopi Chand · Answer

We use interface because: Interface helps to obtain full abstraction in Java. Interface helps to do loose coupling in Java application. Interface helps to obtain multiple inheritances in Java. Get the detail knowledge about use of interface http://www.c-sharpcorner.com/UploadFile/9a9e6f/interface-keyword-in-java/

Akhil Garg · Answer

http://www.c-sharpcorner.com/UploadFile/93126e/difference-between-abstract-class-and-an-interface/ Interface supports multiple inheritance