interface & abstract

Question

When to use interface? when to use abstract class? Explain in detail...

Sanjeeb Lenka · Answer

HI, Use an abstract class When creating a class library which will be widely distributed or reused—especially to clients, use an abstract class in preference to an interface; because, it simplifies versioning. This is the practice used by the Microsoft team which developed the Base Class Library. (COM was designed around interfaces.) Use an abstract class to define a common base class for a family of types. Use an abstract class to provide default behavior. Subclass only a base class in a hierarchy to which the class logically belongs. Use an interface When creating a standalone project which can be changed at will, use an interface in preference to an abstract class; because, it offers more design flexibility. Use interfaces to introduce polymorphic behavior without subclassing and to model multiple inheritance—allowing a specific type to support numerous behaviors. Use an interface to design a polymorphic hierarchy for value types. Use an interface when an immutable contract is really intended. A well-designed interface defines a very specific range of functionality. Split up interfaces that contain unrelated functionality. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable{mso-style-name:"Table Normal";mso-tstyle-rowband-size:0;mso-tstyle-colband-size:0;mso-style-noshow:yes;mso-style-priority:99;mso-style-parent:"";mso-padding-alt:0in 5.4pt 0in 5.4pt;mso-para-margin-top:0in;mso-para-margin-right:0in;mso-para-margin-bottom:10.0pt;mso-para-margin-left:0in;line-height:115%;mso-pagination:widow-orphan;font-size:11.0pt;font-family:"Calibri","sans-serif";mso-ascii-font-family:Calibri;mso-ascii-theme-font:minor-latin;mso-hansi-font-family:Calibri;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;}

Jignesh Trivedi · Answer

hi, please refer http://msdn.microsoft.com/en-us/library/scsyfw1d(v=vs.71).aspx http://codeofdoom.com/wordpress/2009/02/12/learn-this-when-to-use-an-abstract-class-and-an-interface/ hope this will help you.

Maha · Answer

Before understanding interface you must know inheritance first. If you know inheritance then I can explain interface.