39 lines
1.9 KiB
Markdown
39 lines
1.9 KiB
Markdown
---
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layout: pattern
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title: Mediator
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folder: mediator
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permalink: /patterns/mediator/
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pumlid: FSV14SCm20J0Lk82BFxf1akCJKOW3JhizfDNVhkRUktP9AE_Bc2kDr7mKqx5bKSkYJeSuYXr66dFXy517xvvRxBqz7qo8E6BZDSFPDAKCO84zP-IOMMczIy0
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categories: Behavioral
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tags:
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- Java
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- Gang Of Four
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- Difficulty-Intermediate
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---
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## Intent
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Define an object that encapsulates how a set of objects interact.
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Mediator promotes loose coupling by keeping objects from referring to each
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other explicitly, and it lets you vary their interaction independently.
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## Applicability
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Use the Mediator pattern when
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* a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand
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* reusing an object is difficult because it refers to and communicates with many other objects
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* a behavior that's distributed between several classes should be customizable without a lot of subclassing
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## Real world examples
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* All scheduleXXX() methods of [java.util.Timer](http://docs.oracle.com/javase/8/docs/api/java/util/Timer.html)
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* [java.util.concurrent.Executor#execute()](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executor.html#execute-java.lang.Runnable-)
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* submit() and invokeXXX() methods of [java.util.concurrent.ExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ExecutorService.html)
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* scheduleXXX() methods of [java.util.concurrent.ScheduledExecutorService](http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ScheduledExecutorService.html)
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* [java.lang.reflect.Method#invoke()](http://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Method.html#invoke-java.lang.Object-java.lang.Object...-)
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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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