Why do we use Interface? Is it only for Standardiz

Question

Why do we use Interface?

Is it only for Standardization?

Answer 1

Interface provide prototype modal that just contains declaration of functionality of a specific behavior.

and if u want to implement this behavior into class then u must implement this interface in class then class have this behavior functionality or it can have multiple behavior.

because class can implement multiple interface.

Answer 2

The main reason the interfaces are used in languages like C#/Java is because those languages don't support multiple (class) inheritance (see What is the exact problem with multiple inheritance?).

But multiple (interface) implementation is permited allowing classes to be used in diferent ways.

Answer 3

Interface separates the data type from the implementation logic.

Answer 4

An interface is used to describe what an implemented thing can do. So you have the possibility to treat several objects which implementing the same interface as a type of this interface.

For example:

public interface IMyInterface{
    public void DoFirst();
    public int DoSecond();
}


public class A : IMyInterface{
   //class has to implement DoFirst and DoSecond
   public void DoFirst(){
     Console.WriteLine("Blubb1");  
   }

   public int DoSecond(){
     Console.WriteLine("Blubb2");
     return 2;  
   }
}

public class B : IMyInterface{
   //class has to implement DoFirst and DoSecond
   public void DoFirst(){
     Console.WriteLine("Blibb1");  
   }

   public int DoSecond(){
     Console.WriteLine("Blibb2");  
     return 4;
   }
}

The classes implement the Interface in several ways. But you can use them as IMyInterface. For example:

public static void DoMethodsInInterface(IMyInterface inter){
    inter.DoFirst();
    inter.DoSecond();
}


public static void main(){

   DoMethodsInInterface(new A());
   DoMethodsInInterface(new B());
   //Or use it in a List
   List<IMyInterface> interlist = new List<IMyInterface>();
   interlist.Add(new A());
   interlist.Add(new B());
   foreach(IMyInterface inter in interlist){
      inter.DoFirst();
   }

}

I hope this makes a bit clear why interfaces are useful.

Answer 5

Following are the main reasons for the use of interfaces

1. Extensibility
2. Implementation Hiding
3. Accessing object through interfaces
4. Loose Coupling.

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Answer 6

Here's the high level view...

Interfaces play a big role in the concept of Information Hiding.

They basically help you hide the implementation details of your class so that a calling class does has no dependency on that implementation. Therefore, by using interfaces you can modify the implementation without changing the calling class. This all in turns limits the complexity of your code and make it easier to maintain in the long run.

When I first started understanding interfaces they were explained to me as a "contract that provides a description your class." Not sure if that will help you but if you think of an interface for a car you could say that it drives, breaks, and turns. So as long as it gets me from point A to point B, I don't really have to know how those functions are implemented.