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Kotlin for Enterprise Applications using Java EE

You're reading from   Kotlin for Enterprise Applications using Java EE Develop, test, and troubleshoot enterprise applications and microservices with Kotlin and Java EE

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Product type Paperback
Published in Nov 2018
Publisher Packt
ISBN-13 9781788997270
Length 388 pages
Edition 1st Edition
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Author (1):
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Raghavendra Rao K Raghavendra Rao K
Author Profile Icon Raghavendra Rao K
Raghavendra Rao K
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Table of Contents (13) Chapters Close

Preface 1. Kotlin – A First look FREE CHAPTER 2. Kotlin – The Game Changer 3. An Overview of Java EE and Kotlin 4. Kotlin with JSF and CDI 5. Kotlin with JPA and EJB 6. Enterprise Messaging with Kotlin 7. Developing RESTful Services with JAX-RS 8. Securing JAVA EE Applications with Kotlin 9. Implementing Microservices with Kotlin 10. Performance Monitoring and Logging 11. Design Patterns with Kotlin 12. Other Books You May Enjoy

Qualifiers

Qualifiers are required in some cases to resolve conflicts during dependency injection by identifying the correct bean with a qualified name. In the last section, we discussed injecting the dependencies. We injected defaultPreferredLanguage in the IdentityCreator class that was produced by the Producer function of the PreferredLanguageProducer class. If we want to inject another field of the same type, we then have a problem. If we have another function that produces a bean of the PreferredLanguage type, the CDI wouldn't know which one to consider and inject. In order to solve this, we can specify qualifiers, such as the @Named annotation.

@Named is a qualifier that is shipped by the CDI. It is annotated with @Qualifier and can qualify string values for instances to be injected.

Let's say that we want to have several preferredLanguage types, based on a context...

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