Design pattern 1
- 1. Pattern Study - 1 By, D. B. Naga Muruga, Dept of Mechanical Engineering, Sriram Engineering College
- 2. What is a Design Pattern a design pattern is simply a description of a recurring solution to a problem, given a context. The context is the environment, surroundings, situation, or interrelated conditions within which the problem exists.
- 3. Classification Of Design Patterns Purpose - what a pattern does Creational patterns Structural patterns Behavioral pattern J2EE patterns Scope - what the pattern applies to Class Patterns Focus on the relationships between classes and their subclasses- Involve inheritance reuse Object Patterns Focus on the relationships between objects Involve composition reuse
- 4. All the creational patterns define the best possible way in which an object can be instantiated. These describes the best way to CREATE object instances. Now everyone knows the object instance in Java can be created using a new operator. Creational Patterns
- 5. Structural Patterns Structural Patterns describe how objects and classes can be combined to form larger structures. The difference between class patterns and object patterns is that class patterns describe abstraction with the help of inheritance and how it can be used to provide more useful program interface. Object patterns, on other hand, describe how objects can be associated and composed to form larger, more complex structures.
- 6. Behavioral Patterns Behavioral patterns are those which are concerned with interactions between the objects. The interactions between the objects should be such that they are talking to each other and still are loosely coupled. The loose coupling is the key to n-tier architectures. In this, the implementation and the client should be loosely coupled in order to avoid hard-coding and dependencies.
- 7. Creational patterns 1) Abstract Factory 2) Builder 3) Factory method 4) Prototype 5) Singleton - Concern the process of object creation
- 8. Structural patterns 1) Adapter 2) Bridge 3) Composite 4) Decorator 5) Façade 6) Flyweight 7) Proxy -Deal with the composition of classes and objects
- 9. Behavioral pattern 1) Chain of Responsibility 2) Command 3) Interpreter 4) Iterator 5) Mediator 6) Memento 7) Observer 8) State 9) Strategy 10) Template Method 11) Visitor -Deal with the interaction of classes and objects
- 10. J2EE patterns 1) MVC 2) Business Delegate 3) Composite Entity 4) Data Access Object 5) Front Controller 6) Intercepting Filter 7) Service Locator 8) Transfer Object
- 13. How many design patterns? A site says at least 250 existing patterns are used in OO world, including Spaghetti which refers to poor coding habits. The 23 design patterns by GOF are well known, and more are to be discovered on the way. Note that the design patterns are not idioms or algorithms or components.