Using Multiple Interfaces

Environment: .NET / C#

One of the benefits of implementing interfaces instead of inheriting from a class is that you can implement more than one interface at a time. This gives you the power to do multiple inheritance without some of the downside.

To implement multiple interfaces in C#, you separate each included interface with a comma. For example, to include both an Ishape and an IshapeDisplay interface in a Square class, you use the following:

class Square : IShape, IShapeDisplay
{
   ...
}

You then need to implement all the constructs within both interfaces. Listing 1 illustrates the use of multiple interfaces.

Listing 1 - Multi.cs - Implementing Multiple Interfaces in a Single Class

 1:  //  Multi.cs - 
 2:  //-----------------------------------------------------------
 3:
 4:  using System;
 5:
 6:  public interface IShape
 7: {
 8:     // Cut out other methods to simplify example.
 9:     double Area();
10:     int Sides { get; }
11:  }
12:
13:  public interface IShapeDisplay
14:  {
15:     void Display();
16:  }
17:
18:  public class Square : IShape, IShapeDisplay
19:  {
20:     private int InSides;
21:     public  int SideLength;
22:
23:     public int Sides 
24:     {
25:        get { return InSides; }
26:     }
27:
28:     public double Area()
29:     {
30:        return ((double) (SideLength * SideLength));
31:     }
32:
33:     public double Circumference()
34:     {
35:        return ((double) (Sides * SideLength));
36:     }
37:
38:     public Square()
39:     {
40:        InSides = 4;
41:     }
42:
43:     public void Display()
44:     {
45:        Console.WriteLine("\nDisplaying Square information:");
46:        Console.WriteLine("Side length: {0}", this.SideLength);
47:        Console.WriteLine("Sides: {0}", this.Sides);
48:        Console.WriteLine("Area: {0}", this.Area());
49:     }
50:  }
51:
52:  public class Multi
53:  {
54:     public static void Main()
55:     {
56:        Square mySquare = new Square();
57:        mySquare.SideLength = 7;
58:
59:        mySquare.Display();
60:     }
61:  }

Output

Displaying Square information:
Side length: 7
Sides: 4
Area: 49

You can see that two interfaces are declared and used in this listing. In Line 18, you can see that the Square class will implement the two interfaces. Because both are included, all members of both interfaces must be implemented by the Square class. In looking at the code in Lines 23 - 49, you see that all the members are implemented. You can implement multiple interfaces in your own applications in the same way.

Downloads

Download source - MInherit.zip - 1 Kb


About the Author

Bradley Jones

Bradley Jones, in addition to managing CodeGuru, Brad! oversees the Developer.com Newtwork of sites including Codeguru, Developer.com, DevX, VBForums, and over a dozen more with a focus on software development and database technologies. His experience includes development in C, C++, VB, some Java, C#, ASP, COBOL, and more as well as having been a developer, consultant, analyst, lead, and much more. His recent books include Teach Yourself the C# Language in 21 Days, Web 2.0 Heroes, and Windows Live Essentials and Services.
Google+ Profile | Linked-In Profile | Facebook Page

Comments

  • Comment

    Posted by iyanar.k on 04/23/2013 03:48am

    Nice and simple to understand. Keep posting

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Instead of only managing projects organizations do need to manage value! "Doing the right things" and "doing things right" are the essential ingredients for successful software and systems delivery. Unfortunately, with distributed delivery spanning multiple disciplines, geographies and time zones, many organizations struggle with teams working in silos, broken lines of communication, lack of collaboration, inadequate traceability, and poor project visibility. This often results in organizations "doing the …

  • With JRebel, developers get to see their code changes immediately, fine-tune their code with incremental changes, debug, explore and deploy their code with ease (both locally and remotely), and ultimately spend more time coding instead of waiting for the dreaded application redeploy to finish. Every time a developer tests a code change it takes minutes to build and deploy the application. JRebel keeps the app server running at all times, so testing is instantaneous and interactive.

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds