You might ask why you even need some huge reference for Java after using it for years?
You're moving from a verbose, bloated, over-engineered system to a terse and simple system. I think you're looking for something that doesn't exist because it's not how Ruby programmers work -- they use a language small enough to actually keep in your head and that's a huge part of the productivity to be had.
I don't usually look into the Java programming reference or tutorial anymore. However, typically every project involves some new technology, Hibernate, Spring, Groovy, whatever, so my feeling is that it's actually the job of the Software Developer to constantly learn new things. It's nice if the documentation doesn't get in my way then. Maybe I am mistaken, though, and it feels totally different for developers using other languages.
My ride with RoR hasn't been smooth so far. Far from having my first web app running within minutes. Instant Rails didn't work at all, and I spent hours trying to find a database driver for MySQL for Ruby. It's all very confusing. I suspect there is already a database driver bundled with RoR, but how would I know (documentation, where are you)? Googling only led me to some strange page where you could compile your own driver from C source code (and with what compiler, if I am on windows), which presumably was in some kind of alpha stage.
At least with Java I know that there usually exists a stable and proven solution... The training wheel analogy was maybe not so bad at all: Java applications just tend to be more stable than the scripting stuff. And other than bikes with training wheels in the real life, Java is also faster.
You're moving from a verbose, bloated, over-engineered system to a terse and simple system. I think you're looking for something that doesn't exist because it's not how Ruby programmers work -- they use a language small enough to actually keep in your head and that's a huge part of the productivity to be had.