“Rocket Propelled Java” is about being more productive by writing less boilerplate code (slides on slideshare).
In his talk, Andres Almiray showed some tools to make your code more compact while keeping or even improving readability.
The first one is lombok and lombok-pg which use Java annotations to generate a lot of boiler plate code (slides 3-6)
Similar, you can use Groovy AST transformations to create things like immutables or singletons correctly (“There are 5-6 ways to create singletons. Only two of them are correct”, slides 7-9)
Note: You might be worried to add Groovy to a pure Java project. You don’t have to. Just use it for the AST transformations to stop wasting time on writing code that only makes your compiler happy. Use Groovy as a “boilerplate code buster.”
If you ever wanted to use “Design by Contract“, GContracts is for you.