Keng,
The whole purpose of javadoc is to expose, "WHAT" a method or a class or a type is doing, and not "HOW"; In case of interfaces, you write the whole java
doc, the implementation will simply be:
(This is default behavior for Eclipse
IDE as well); Simply because interface javadoc tells you what can be expected consistently from implementations, as a client using that code, I DO NOT care "HOW" it is being done; oh and if implementation is different , then this is breaking of the contract ... NOT GOOD!
To Original Poster,
Javadoc everything, except for fields (On my open source frameworks, some of our developers javadoc even the fields (I just think it clutters up additional space)).
This is my personal opinion (and what I think is the best practices), people write stuff all the time that is devoid of any documentation (not good IMHO)... and think that its the best, so whatever works for you guys! =)
Trilochan.