Use of Design Patterns to improve code maintainability

[amadoran]

Adapter Pattern.

In this snippet of the code i found that if you want to send a message in a different way you should use this design pattern to transform the data and make it possible to use.

Singleton Pattern.
If we analyse the project the classes Book, MailServerInfo and Member are in the same package but they are just data for the database. In this case we could use just a single instance of an object to encapsulate this fields, that's why we use the singleton pattern.