codestyle; put javadoc before or after annotation?

Before the annotation, since the annotation is code that "belongs" to the class. See examples with javadoc in the official documentation.

Here's random example I found in another official Java page:

/**
 * Delete multiple items from the list.
 *
 * @deprecated  Not for public use.
 *    This method is expected to be retained only as a package
 *    private method.  Replaced by
 *    {@link #remove(int)} and {@link #removeAll()}
 */
@Deprecated public synchronized void delItems(int start, int end) {
    ...
}

I agree with the answers already given.

Annotations are part of the code while javadoc is part of the documentation (hence the name).

So for me it seams reasonable to keep the code parts together.

Aside from the coding standard, it seems that javadoc tool doesn't process the javadoc comments if they are placed after the annotations. Works fine otherwise.

It all comes down to readablity. In my opinion code is more readable with the Annotations directly above the method/field.