From Oracle/Sun:
http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html
From Google:
http://google-styleguide.googlecode.com/svn/trunk/javaguide.html
Java Coding Style by Achut Reddy
http://www.scribd.com/doc/15884743/Java-Coding-Style-by-Achut-Reddy
Good compilation from few books
http://www.ambysoft.com/essays/javaCodingStandards.html
The Elements of Java™ Style
http://its.lnpu.edu.ua/edocs1/new_doc/en/Vermeulen%20A.The%20elements%20of%20Java%20style.2001.pdf
