What are the top 3 productivity improving libraries for core java?
<p>Compared with other languages, Java sometimes is pretty "chatty" and some of the core libraries are considered cumbersome by a lot of programmers. Over the last years an tremendous zoo of small libraries has evolved, which try to "fix" a single aspect of these e.g. Joda Time, guava-libraries, lambdaj</p>

<p>What are the top three libraries that can improve productivity when working with core Java? </p>
