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JAVA/J2EE INTERVIEW QUESTIONs:- Explain many types of design pattern?
Factory design pattern:-Defines an interface for creating an object , but lets the sub class decide which class to instantiate.
Abstract factory design pattern:-Provides an interface for creating families of related or dependant objects without specifying their concrete classes.
Relation between factory and abstract factory pattern:- When factory pattern is applied to a family of products and an interface is provided for the same,abstract design pattern is formed.
Adaptar design pattern:-
•Converts interface of a class into interface that client expects
•Allows classes to work together which could otherwise not be possible
Builder design pattern and its advantages: - Moves the construction logic of the object from the object class to a builder classImproves.
•Object construction
•Making new changes
•Modular design
Command design pattern:- Encapsulates a request as object and supports parametrizing other objects.
Composite design pattern:- describes that a group of objects are to be treated in the same way as a single instance of an object.
Decorator design pattern: -
•responsibilities to an object added dynamically
•provide a flexible alternative to sub classing for extending functionality
Facade design pattern: -
•Provides a unified interface to a set of interfaces in a sub system
•Defines higher level interface that makes sub system easier to use
Flyweight design pattern:- An object that minimizes memory use by sharing as much data as possible with other similar objects.
Mediator design pattern: -
•Define an object that encapsulates details and other objects interact with such object
•The relationships are loosely decoupled
Observer design pattern:- Defines one to many dependency between objects so that when one object changes state all its dependants are notified and updated automatically.
Prototype design pattern:- Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Singleton design pattern:- Ensures a class has only one instance and provides a global point access to it.
State design pattern:- Allows an object to change its behavior when its internal state changes.
Template design pattern:-
•Defines skeleton of algorithms in a method deferring some steps to sub classes
•Allows sub classes to redefine some steps without changing the algorithm
Memento design pattern:- Deals with storing and retrieving objects as and when required.
Also see the following video on Java Builder Design Pattern as follows:-
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Contributed by:
Shivprasad koirala Koirala
I am a Microsoft MVP for ASP/ASP.NET and currently a CEO of a small
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