39 lines
1.0 KiB
Markdown
39 lines
1.0 KiB
Markdown
---
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layout: pattern
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title: Factory Method
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folder: factory-method
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permalink: /patterns/factory-method/
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categories: Creational
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tags:
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- Java
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- Difficulty-Beginner
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- Gang Of Four
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---
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## Also known as
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Virtual Constructor
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## Intent
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Define an interface for creating an object, but let subclasses
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decide which class to instantiate. Factory Method lets a class defer
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instantiation to subclasses.
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## Applicability
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Use the Factory Method pattern when
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* a class can't anticipate the class of objects it must create
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* a class wants its subclasses to specify the objects it creates
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* classes delegate responsibility to one of several helper subclasses, and you want to localize the knowledge of which helper subclass is the delegate
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## Known uses
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* java.util.Calendar
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* java.util.ResourceBundle
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* java.text.NumberFormat#getInstance()
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## Credits
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* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
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