How are annotations implemented

[areale]

My question is pretty simple in its form, but I could not manage to
find anything about it searching the web.
How are annotations implemented in the JVM?
More specifically, how are they represented in the bytecode wrt
different retentions policies?

I'd be very grateful if someone can help me or point me some useful
resource about it.

Thank you,
andrea

 

[Joshua Cranmer]

My question is pretty simple in its form, but I could not manage to
find anything about it searching the web.
How are annotations implemented in the JVM?
More specifically, how are they represented in the bytecode wrt
different retentions policies?

Unfortunately, the JVM as published in HTML format does not represent
the changes in Java 5 or 6, so you have to make do with this PDF file:
<http://java.sun.com/docs/books/jvms/second_edition/ClassFileFormat-Java5.pdf>.

That is the class file format for Java 5 (Java 6 has another 100 pages
or so of addendum, thanks to a detailed specification of bytecode
verification that is beyond the scope of this post and is pretty much
useless for everyone except compiler and JVM writers); the annotation
information is spread out among several attributes.