34 lines
1.2 KiB
Markdown
34 lines
1.2 KiB
Markdown
---
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layout: pattern
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title: Flyweight
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folder: flyweight
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permalink: /patterns/flyweight/
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categories: Structural
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tags:
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- Java
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- Gang Of Four
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---
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**Intent:** Use sharing to support large numbers of fine-grained objects
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efficiently.
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**Applicability:** The Flyweight pattern's effectiveness depends heavily on how
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and where it's used. Apply the Flyweight pattern when all of the following are
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true
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* an application uses a large number of objects
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* storage costs are high because of the sheer quantity of objects
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* most object state can be made extrinsic
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* many groups of objects may be replaced by relatively few shared objects once extrinsic state is removed
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* the application doesn't depend on object identity. Since flyweight objects may be shared, identity tests will return true for conceptually distinct objects.
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**Real world examples:**
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* [java.lang.Integer#valueOf(int)](http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#valueOf%28int%29)
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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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