Design patterns represent the best practices used by java design patterns with examples pdf object-oriented software developers. Design patterns are solutions to general problems that software developers faced during software development. These solutions were obtained by trial and error by numerous software developers over quite a substantial period of time.
This tutorial will take you through step by step approach and examples using Java while learning Design Pattern concepts. This reference has been prepared for the experienced developers to provide best solutions to certain problems faced during software development and for un-experienced developers to learn software design in an easy and faster way. Before you start proceeding with this tutorial, I’m making an assumption that you are already aware about basic java programming concepts. Design Pattern in Software development.
According to these authors design patterns are primarily based on the following principles of object orientated design. Design Patterns have two main usages in software development. Design patterns provide a standard terminology and are specific to particular scenario. For example, a singleton design pattern signifies use of single object so all developers familiar with single design pattern will make use of single object and they can tell each other that program is following a singleton pattern. Design patterns have been evolved over a long period of time and they provide best solutions to certain problems faced during software development.
Learning these patterns helps un-experienced developers to learn software design in an easy and faster way. These patterns can be classified in three categories: Creational, Structural and behavioral patterns. We’ll also discuss another category of design patterns: J2EE design patterns. These design patterns provides way to create objects while hiding the creation logic, rather than instantiating objects directly using new operator. This gives program more flexibility in deciding which objects need to be created for a given use case.
These design patterns concern class and object composition. Concept of inheritance is used to compose interfaces and define ways to compose objects to obtain new functionalities. These design patterns are specifically concerned with communication between objects. These design patterns are specifically concerned with the presentation tier. These patterns are identified by Sun Java Center. Factory pattern is one of the most used design patterns in Java.
This type of design pattern comes under creational pattern as this pattern provides one of the best ways to create an object. In Factory pattern, we create object without exposing the creation logic to the client and refer to newly created object using a common interface. Create concrete classes implementing the same interface. Create a Factory to generate object of concrete class based on given information. Use the Factory to get object of concrete class by passing an information such as type.
Circle and call its draw method. Rectangle and call its draw method. Square and call its draw method. Abstract Factory patterns works around a super-factory which creates other factories.