ex-08-04

Programming Csharp Source Code(代码) Programming Csharp Source Code

//Example 08-04: Overriding an interface implementation

using System;

interface IStorable
{
   void Read();
   void Write();
}

// Simplify Document to implement only IStorable
public class Document : IStorable
{
   // the document constructor
   public Document(string s) 
   {
      Console.WriteLine(
         "Creating document with: {0}", s);
        
   }
    
   // Make read virtual
   public virtual void Read()
   {
      Console.WriteLine(
         "Document Read Method for IStorable");        
   }

   // NB: Not virtual!
   public void Write()
   {
      Console.WriteLine(
         "Document Write Method for IStorable");  
   }

}

// Derive from Document
public class Note : Document
{
   public Note(string s):
      base(s)
   {
      Console.WriteLine(
         "Creating note with: {0}", s);
   }

   // override the Read method
   public override void Read()
   {
      Console.WriteLine(
         "Overriding the Read method for Note!");
   }

   // implement my own Write method
   public  void Write()
   {
      Console.WriteLine(
         "Implementing the Write method for Note!");        
   }
} 
public class Tester
{
 
   static void Main()
   {
      // create a document object
      Document theNote = new Note("Test Note");
      IStorable isNote = theNote as IStorable;
      if (isNote != null)
      {
         isNote.Read();
         isNote.Write();
      }

      Console.WriteLine("\n");

      // direct call to the methods
      theNote.Read();
      theNote.Write();

      Console.WriteLine("\n");

      // create a note object
      Note note2 = new Note("Second Test");
      IStorable isNote2 = note2 as IStorable;
      if (isNote != null)
      {
         isNote2.Read();
         isNote2.Write();
      }

      Console.WriteLine("\n");

      // directly call the methods
      note2.Read();
      note2.Write();
   }
}