A topic we recently discussed in CS-343 was Factory Design Patterns. The factory design pattern is an object-oriented design pattern that deals with the problem of creating objects without specifying the class of the object that will be created. Creating an object usually requires complex processes, which may lead to a lot of code duplication and an insufficient level of abstraction. Factory design patterns handle problems like this by defining a separate method for creating objects.
http://javadesign-patterns.blogspot.com/p/factory-desig.html
I chose to write this week’s blog on this example of a Factory Design Pattern because I thought it was a simple example that makes understanding Factory Designs easy and also gives readers a straightforward understanding of Factory Designs.
The blog lists when to use factory patterns in a straightforward manner by stating that you can use factory patterns when a class does not know which class of objects it must create, a class specifies its sub-classes to specify which objects to create, or when at runtime you need to create an object based on input parameter.
The blog then gives a good example of Factory Design by imagining that we want to develop a Media Player application, which should play mp3 and mp4 format audio and video files.
In the example, the author creates a Decoder interface, a MP3Decoder class, a MP4Decoder class, and a player class. The problem that arises is that the classes MP3Decoder and MP4Decoder are tightly coupled with the Player class. This could become a problem if Player needs to support a new format because then a new decoder needs to be added to the Player class, so every time you would have to modify the Player class.
To fix this problem, the factory design pattern can be used. The author applies the factory pattern in this example by introducing a DecoderFactory class and moves the Decoder objects from the Player class to this new one, then by modifying the Player class to use the new factory class. With this new implementation, if the Player class needs to support a new format then no modification is required in the Player class because you will only need to put the new type of decoder in the Factory class.
I chose this blog because it efficiently explained the Factory design pattern, which we are learning in class right now, and gave a new example that helps further my understanding of the design pattern even more. It was simple and straightforward and did not leave me confused when trying to understand it.
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