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

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.

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.

@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)