What is javax inject Named annotation supposed to be used for

Question

I am trying to understand the javax inject package and I am not clear what the javax inject Named annotation is supposed to be used for  The Javadoc does not explain the the idea behind it    Javadoc is at http   download oracle com javaee 6 api javax inject Named html  I am using Spring 3 0 to write some sample programs  by putting  Named on a bean it seems to add it to the bean factory but the Javadoc description is so light I can t tell if that is the standard behavior or Spring specific behavior   My questions are    What is the difference between  Named and  Qualifier How are you supposed to tell the Runtime system a class should be injectable in other classes what s the annotation for that  The equivalent of  Component in Spring    Update 1 there is an excellent explanation of  Named and  Qualifier at Nice article about  Named and  Qualifier https   dzone com articles java-ee6-cdi-named-components thanks  xmedeko for linking to it the comment below

User · Answer

Inject instead of Spring   s  Autowired to inject a bean   Named instead of Spring   s  Component to declare a bean   Those JSR-330 standard annotations are scanned and retrieved the same way as Spring annotation  as long as the following jar is in your classpath

User · Answer

Regarding  2  according to the JSR-330 spec      This package provides dependency   injection annotations that enable   portable classes  but it leaves   external dependency configuration up   to the injector implementation    So it s up to the provider to determine which objects are available for injection    In the case of Spring it is all Spring beans    And any class annotated with JSR-330 annotations are automatically added as Spring beans when using an AnnotationConfigApplicationContext

User · Answer

Use  Named to differentiate between different objects of the same type bound in the same scope     Named  maxWaitTime   public long maxWaitTimeMs    Named  minWaitTime   public long minWaitTimeMs    Without the  Named qualifier  the injector would not know which long to bind to which variable    If you want to create annotations that act like  Named  use the  Qualifier annotation when creating them  If you look at  Named  it is itself annotated with  Qualifier

User · Answer

The primary role of the  Named annotation is to define a bean for the purpose of resolving EL statements within the application  usually through JSF EL resolvers  Injection can be performed using names but this was not how injection in CDI was meant to work since CDI gives us a much richer way to express injection points and the beans to be injected into them

[java] What is javax.inject.Named annotation supposed to be used for?

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