An application framework is a software library that provides a fundamental structure to support the development of applications for a specific environment. An application framework acts as the skeletal support to build an application. The intention of designing application frameworks is to lessen the general issues faced during the development of applications. This is achieved through the use of code that can be shared across different modules of an application. Application frameworks are used not only in the graphical user interface (GUI) development, but also in other areas like web-based applications.
Application frameworks are not a recently emerged idea. Some of the old application frameworks that are still used today are the SmallTalk user interface framework, MacApp (for Macintosh), and Struts (for Web-based Java applications).
We can start with the interface to define a signature
The Abstract calss
The sealed class
