Tec Bar » Design Patterns

Proxy Pattern

James — Tue, 21 Apr 2015 23:17:28 +0000

The intent of Proxy Pattern is to provide a placeholder for an object to control access to it, and add a wrapper and delegation to protect the real component from undue complexity. The reason to need the placeholder is sometimes … Continue reading →

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Command Pattern

James — Fri, 17 Apr 2015 22:14:56 +0000

Command pattern encapsulates a request under an object as command, and passed to invoker object. It allows the parameterization of clients with different requests, queue or log requests. Normally, command pattern can be applied when we need to issue requests … Continue reading →

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Template Method Pattern

James — Mon, 13 Apr 2015 23:45:27 +0000

Template Method pattern defines the skeleton of an algorithm, and defer some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm’s structure. Implementation checklist abstract template class – a) defines abstract primitive … Continue reading →

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Façade Pattern

James — Tue, 07 Apr 2015 22:51:30 +0000

Façade pattern hides the complexities of the system, and provides a simpler interface to clients. Façade wraps a complicated subsystem with a simpler interface, and decouples the subsystems from its clients. Example: In the class diagram below, we can see: … Continue reading →

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Prototype Pattern

James — Fri, 03 Apr 2015 23:58:38 +0000

Prototype pattern implements a prototype interface which tells to create a clone of the current object. This pattern is used when creation of object directly is costly. The Prototype pattern allows an object to create customized objects without knowing their … Continue reading →

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Abstract Factory Pattern

James — Thu, 26 Mar 2015 00:36:33 +0000

Abstract Factory Pattern provides an interface for creating a factory of related objects without explicitly specifying their classes. In other words, the Abstract Factory is a super-factory which creates other factories (Factory of factories). Implementation In the above URL class … Continue reading →

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Factory Pattern

James — Sat, 21 Mar 2015 08:23:21 +0000

Factory pattern is one of most used design pattern in Java, and it defines an interface to create the object without exposing the creation logic to the client, and has internal logic to decide which class to instantiate. TrackingAgent interface … Continue reading →

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Strategy Pattern

James — Thu, 19 Mar 2015 07:06:32 +0000

The intent of Strategy pattern is to define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets a class behavior or its algorithm can be changed at run time. It captures the abstraction in an interface, … Continue reading →

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Singleton Pattern

James — Thu, 12 Mar 2015 21:42:51 +0000

Singleton pattern is a creational design pattern. It ensures a class has only one instance created, and provides a global point of access to it. The implementation includes just-in-time initialization and initialization on first use. Singleton class is one of … Continue reading →

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Decorator Pattern

James — Thu, 12 Mar 2015 00:41:47 +0000

Decorator pattern a design pattern that allows behavior to be added to an individual object without affecting the behavior of other objects from the same class. Decorators provide a flexible alternative to subclass for extending functionality. The decorator pattern is … Continue reading →

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