1Z0-819 Annotations 4

Question 1

What is the purpose of the @Native meta-annotation in Java?

Accepted Answer

It indicates that a constant field may be referenced from native code

Answer

@Native (java.lang.annotation.Native) marks a constant-valued field that may be referenced from native code, hinting to tools to generate header files.

Question 2

Which annotation was introduced in Java 9 to indicate that a module exports a package for use only by specific other modules?

Accepted Answer

None — this is a module-info.java keyword, not an annotation

Answer

Qualified exports in module-info.java are declared with the 'exports ... to ...' syntax, not with a Java annotation.

Question 3

Given a repeatable annotation @Tag and its container @Tags, which method should you use to retrieve all @Tag instances from a method at runtime?

Accepted Answer

method.getAnnotationsByType(Tag.class)

Answer

getAnnotationsByType(Tag.class) transparently unwraps the container and returns all repeated @Tag annotations as a flat array.

Question 4

Which of the following correctly defines a single-element annotation where the element is named 'value'?

Accepted Answer

public @interface Timeout { long value(); }

Answer

The special element name 'value' allows callers to omit the element name: @Timeout(500) instead of @Timeout(value=500).

Question 5

An annotation processor that generates new source files implements which interface from javax.annotation.processing?

Accepted Answer

Processor

Answer

javax.annotation.processing.Processor is the interface annotation processors implement; AbstractProcessor provides a convenient base class.

(1Z0-819) Oracle Java SE 11 Developer Practice Test

(1Z0-819) Oracle Java SE 11 Developer Practice Test

1Z0-819 Annotations 4