The list of Web sites (with URLs):
This is the place from which the JDK originates and is often the first site that Java developers go to download a copy of the JDK and documentation. But beyond that, it is also a good source for information on the entire Java platform, including a very rich section on the JVM itself (Hotspot), which describes the internals of the JVM to a surprising depth.
The Java.NET site is a smorgasbord of open-source projects, documentation, blogs, wikis, news, and other community resources. It's a motherlode of information on Java technology, possibly too much. For all that though, cruising through the list of projects can lead to some real gems such as the FEST-Swing project, which aims to create a "fluent interface" for building Swing applications, making them vastly simpler to create unit tests around.
Created by Floyd Marinescu, founding editor-in-chief of The ServerSide, InfoQ differs from many of the other resources listed here in that it is explicitly technology-neutral, covering not only Java code but also .NET and Ruby and offering great coverage of agile approaches and insights. Though the commenting community on InfoQ isn't as large or as diverse as that of TheServerSide, the discussion is usually more tame and less hostile.
Often called "the the Slashdot of Java," TheServerSide was the first place that enterprise Java topics were openly questioned, hotly debated, and aggressively pursued. Some of the earliest thoughts around lightweight containers (as typified by Spring) occurred here and many of the individuals now considered to be "thought leaders" in the Java community emerged here. Although more recently the debates have sometimes taken on the character of shrill shouting matches, TSS will always be the original home of much of what turned into the Java ecosystem we now live within; as such, it will always be a source of information, historical if nothing else.
DZone began life as a resource for Java developers, but more recently has begun to branch out into the other technology sectors, including .NET and Ruby, as well as several other topical "zones" of coverage. As such, while it's possible for the Java developer to focus entirely on just the Java zone, some cross-pollination does occur and it's the wise developer who will take advantage of that.
* IBM® developerWorks
If you're reading this article, then you've already found dW. In the interest of full disclosure, I must note that I have contributed articles other than this one to this site, but I can say with integrity that dW stands as a great resource for articles and material on Java coding and the JVM. In particular, be sure to check out Java theory and practice, a long-running series by Brian Goetz, which includes a three-part description of the JVM garbage collector that introduces the core concepts of GC in a surprisingly approachable way.
After a long hiatus, JavaWorld has returned to its youthful glory with a revamped look, high-quality technical content, and a handy topic taxonomy for quickly finding the types of articles you seek. Don't miss the extensive archives, which date back to its inception and include articles by some of the Java community's most notable contributors.
Created by Bill Venners, Artima has evolved into a huge collection of articles, blogs, and interviews, not all of it entirely focused on Java development, and has some of the biggest names in the Java space writing there. (Check out Bill Joy's disbelief over the complexity of the Java language after Java 5 was released and the example he uses to justify his worries — Enum<> — as a classic example.) Well worth