Given the code sample: And: And: And the next fragment from beans.xml: And this injection point: @Inject GenericMessenger messageHandler; Which type would be injected at run time and referenced by…

Question

Options

• ASmsHandler
• BMsgHandler
• CNone of the above. An exception would be thrown due to ambiguous bean references.
• DGenericMessenger

• A
  4% (2)
• B
  2% (1)
• C
  7% (3)
• D
  87% (39)

Explanation

Option D is correct because in CDI (Contexts and Dependency Injection), @Alternative beans must be explicitly activated in beans.xml to participate in injection. Based on the code fragments, SmsHandler and MsgHandler are annotated with @Alternative, but the beans.xml shown does not enable either of them under <alternatives>, leaving GenericMessenger itself as the sole eligible bean for the injection point.

Option A (SmsHandler) and Option B (MsgHandler) are wrong for the same reason: they are @Alternative beans that are declared but not activated, so CDI excludes them from consideration entirely. Option C is wrong because there is no ambiguity - alternatives that are not enabled in beans.xml are invisible to the CDI container, so only one candidate (GenericMessenger) remains.

Memory tip: Think of CDI alternatives as "opt-in substitutes" - declaring @Alternative on a class is like writing your name on a substitute list, but you only get called in if beans.xml activates you. If no one activates the substitutes, the original teacher (GenericMessenger) still runs the class.

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