AOP aims at reducing the amount of "tangled" code by which we mean code that might be implemented in different classes if a OOP language is used but still share important secondary requirements. Such requirements are said to cross-cut the system's basic functionality and are difficult to develop and maintain using non-AOP programming paradigms. Cross-cutting functionality can be thought of as functionalty spanning many objects.

The design patterns are strategies for solving common object-oriented design problems. Using the design patterns you can make your code more flexible, reusable and maintainable. We must use the design patterns during the analysis and requirement phase of SDLC (Software Development Life Cycle).

List, Set and Map interfaces