Basic Differences between Abstract class and Interface

Behaviour

Abstract Class

Interface

Multiple Inheritance

Not Possible

Possible

Inheritance Chain(of same type)

Possible

Not Possible

(does not fall under the inheritance chain of same type)

Concrete Functionality

Possible

Not Possible

Private Members

Not Possible

Possible

Type can be declared as method input parameter

Not Possible

(because instance could not be created)

Possible

(acceptable with fully implemented instance is being passed)

Structs can implement

Not Possible

Possible

Every member needs to be implemented

No

Yes

We can have the interface as the input type for some method which accepts only the objects which completely implements this interface. Following example shows this:

<asp:Button id="Button1" runat="server" OnClick="Goooooogle"/>

public partial class TestViewState_Default : System.Web.UI.Page

{

protected void Goooooogle(object sender, EventArgs e)

{

    myClass myclass = new myClass();

    DoSomeAction(myclass);

}

private void DoSomeAction(myInterface myinterface)

{

    Response.Write(myinterface.myfield.ToString());

}

public class myClass:myInterface

{

    int_ field;

    public int myfield

    {

        get { return 12; }

        set {_ field = value; }

    }

    public int getId()

    {

        return 190;

    }

}

public interface myInterface

{

   int myfield{get; set;}

   int getId();

}

}

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Originally posted on Things on Tech.