title:Fluent Interface

folder:fluentinterface

permalink:/patterns/fluentinterface/

categories:Architectural

tags:Java

categories:Other

tags:

-Java

-Difficulty-Intermediate

**Intent:** A fluent interface provides an easy-readable, flowing interface, that often mimics a domain specific language. Using this pattern results in code that can be read nearly as human language.

**Implementation:**

A fluent interface can be implemented using any of

* Method Chaining - calling a method returns some object on which further methods can be called.

* Static Factory Methods and Imports

* Named parameters - can be simulated in Java using static factory methods.

![Fluent Interface](./etc/fluentinterface.png"Fluent Interface")

**Applicability:** Use the Fluent Interface pattern when

* you provide an API that would benefit from a DSL-like usage

*[Java 8 Stream API](http://www.oracle.com/technetwork/articles/java/ma14-java-se-8-streams-2177646.html)

*[Google Guava FluentInterable](https://github.com/google/guava/wiki/FunctionalExplained)

*[JOOQ](http://www.jooq.org/doc/3.0/manual/getting-started/use-cases/jooq-as-a-standalone-sql-builder/)

**Credits**

*[Fluent Interface - Martin Fowler](http://www.martinfowler.com/bliki/FluentInterface.html)

*[Evolutionary architecture and emergent design: Fluent interfaces - Neal Ford](http://www.ibm.com/developerworks/library/j-eaed14/)

*[JOOQ](http://www.jooq.org/doc/3.0/manual/getting-started/use-cases/jooq-as-a-standalone-sql-builder/)

*[Mockito](http://mockito.org/)

*[Java Hamcrest](http://code.google.com/p/hamcrest/wiki/Tutorial)

**Credits**

*[Fluent Interface - Martin Fowler](http://www.martinfowler.com/bliki/FluentInterface.html)

*[Evolutionary architecture and emergent design: Fluent interfaces - Neal Ford](http://www.ibm.com/developerworks/library/j-eaed14/)

*[Internal DSL](http://www.infoq.com/articles/internal-dsls-java)