Ok, lets recommend resources in following categories: ebooks, blogs, forums.
The JavaSeries is supported, endorsed, and authored by the creators of the Java technology at Sun Microsystems, Inc. It is the official place to go for complete, expert, and definitive information on Java technology. The books in this Series provide the inside information you need to build effective, robust, and portable applications and applets. The Series is an indispensable resource for anyone targeting the Java 2 platform.
Actually this quote is 100% true.
The recommendation goes to Artima.
Artima Developer is an online community where developers learn from experts in the software industry as well as interact, share information, and learn from each other.
Javaranch – In two words – great forum. There are lot of interesting discussions at all levels (from beginner to expert). Nearly 200,000 members. Book writers are frequent forum visitors.