Implementing More Than One Interface

Classes can derive from only one class (and if you don't explicitly derive from a class, then you implicitly derive from Object). Classes can implement any number of interfaces. When you design your class, you can choose not to implement any interfaces, you can implement a single interface, or you can implement two or more interfaces.

For example, in addition to IStorable, you might have a second interface, ICompressible, for files that can be compressed to save disk space. If your Document class can be stored and compressed, you might choose to have Document implement both the IStorable and ICompressible interfaces.

IStorable and ICompressible, implemented by Document

using System;



namespace InterfaceDemo

{

 interface IStorable

 {

     void Read();

     void Write(object obj);

     int Status { get; set; }



 }



 // here's the new interface



    interface ICompressible

    {

        void Compress();

        void Decompress();


 }





 // Document implements both interfaces

    public class Document : IStorable, ICompressible

 {

     // the document constructor

     public Document(string s)

     {

         Console.WriteLine("Creating document with: {0}", s);

  

     }



     // implement IStorable

     public void Read()

     {

         Console.WriteLine(

             "Implementing the Read Method for IStorable");     
}



     public void Write(object o)

     {

         Console.WriteLine(

             "Implementing the Write Method for IStorable");

     }



     public int Status

     {

         get { return status; }

         set { status = value; }

     }



        // implement ICompressible

        public void Compress() 

        { 

            Console.WriteLine("Implementing Compress");
 }

    

        public void Decompress() 

        { 

            Console.WriteLine("Implementing Decompress"); 

        }





     // hold the data for IStorable's Status property

     private int status = 0;

 }





class Tester

{

   public void Run()

   {

       Document doc = new Document("Test Document");

doc.Status = -1;

       doc.Read();

          doc.Compress();

       Console.WriteLine("Document Status: {0}", doc.Status);

   }



   [STAThread]

   static void Main()

   {

      Tester t = new Tester();

      t.Run();

   }

}

}



Output:

Creating document with: Test Document


Implementing the Read Method for IStorable

Implementing Compress

Document Status: -1

RELATED POST

UNIT TESTING PART ONE

UNIT TESTING PART TWO

UNIT TESTING PART THREE

GUI TESTING

WINDOWS COMPLIANCE GUI TESTING PART ONE

WINDOWS COMPLIANCE GUI TESTING PART TWO

WINDOWS COMPLIANCE GUI TESTING PART THREE

WINDOWS COMPLIANCE GUI TESTING PART FOUR VALIDATION TESTING

WINDOWS COMPLIANCE GUI TESTING PART FIVE CONDITION TESTING

WINDOWS COMPLIANCE GUI TESTING PART SIX GENERAL CONDITION TESTING

CONDITION TESTING

TESTING CONDITIONS PART ONE

TESTING CONDITIONS PART TWO

TESTING CONDITIONS PART THREE

TESTING CONDITIONS PART FOUR

SPECIFIC FIELD TESTING

USABILITY TESTING

INTEGRATION TESTING

INTEGRATION TESTING PART ONE

INTEGRATION TESTING PART TWO

INTEGRATION TESTING PART THREE

INTEGRATION TESTING PART FOUR

INTEGRATION TESTING PART FIVE

INTEGRATION TEST STANDARDS

INTEGRATION TEST STANDARDS PART TWO