Re: Annotation syntax in the JLS?

From:
Tom Anderson <twic@urchin.earth.li>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 12 Apr 2009 21:21:35 +0100
Message-ID:
<alpine.DEB.1.10.0904122116440.25482@urchin.earth.li>
On Sun, 12 Apr 2009, Joshua Cranmer wrote:

Tom Anderson wrote:

@Foo({@Bar, @Baz, @Qux})

I don't know what that means, though.


The annotation @Foo containing a value which is an array of annotations,
specifically @Bar, @Baz and @Qux.

A better example (one that I've actually used):
@Options({
 @Option(name="tabWidth", type=int.class, def="8"),
 @Option(name="incWidth", type=int.class, def="4"),
 @Option(name="lineWidth", type=int.class, def="80")
})


Ahaa, of course, thank you. I was being rather dense and failing to make
the connection to annotations which have values (despite the fact that i'd
already written one!). Your example makes excellent sense - you're not
allowed to have multiple annotations of the same type on a class, so you
make a container annotation to hold them.

The only annotations i really use are the JUnit ones and SuppressWarnings
(with only the "unchecked" and "serial" values). I don't do EJB or JPA,
for instance, where i understand they get more play, and perhaps because i
haven't seen them in action, i've never written any of my own. Hence, i'm
really quite ignorant about them.

tom

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