36 lines
1.3 KiB
Markdown
36 lines
1.3 KiB
Markdown
---
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layout: pattern
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title: Value Object
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folder: value-object
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permalink: /patterns/value-object/
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categories: Creational
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tags:
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- Instantiation
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---
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## Intent
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Provide objects which follow value semantics rather than reference semantics.
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This means value objects' equality are not based on identity. Two value objects are
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equal when they have the same value, not necessarily being the same object.
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## Class diagram
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## Applicability
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Use the Value Object when
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* You need to measure the objects' equality based on the objects' value
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## Real world examples
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* [java.util.Optional](https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html)
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* [java.time.LocalDate](https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html)
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* [joda-time, money, beans](http://www.joda.org/)
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## Credits
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* [Patterns of Enterprise Application Architecture](http://www.martinfowler.com/books/eaa.html)
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* [VALJOs - Value Java Objects : Stephen Colebourne's blog](http://blog.joda.org/2014/03/valjos-value-java-objects.html)
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* [Value Object : Wikipedia](https://en.wikipedia.org/wiki/Value_object)
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* [J2EE Design Patterns](https://www.amazon.com/gp/product/0596004273/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596004273&linkCode=as2&tag=javadesignpat-20&linkId=f27d2644fbe5026ea448791a8ad09c94)
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