And now its 2 years later. Has Java gotten easy?
I use both Java and Ruby on Rails extensively. I've been comparing the languages and environments and tweeting about them for years and am quite critical about both of them at times. I have to say, with Spring Boot and Spring Cloud written by the Pivotal people, Java has now gotten easier than Rails. Spring Boot has embraced convention just as Rails has but the convention is production-grade. Rails convention is minimalistic and meant for development only. Before Spring Boot, I would suggest Rails over Java/Spring to any startup. After Spring Boot, its Java no contest.
Java JVMs are also maintained for 10 years vs. Ruby maintained for only 2 years. Even medium sized companies cant do continuous upgrades against languages that quickly. Java has also embraced the syntactic sugar that Ruby originally built in Java's 7, 8, and soon now 9.
Keep in mind this is independent of front-end MVC javascript frameworks and libraries such as AngularJS or React do seem to interact with Ruby/Rails equivalently with Java/Spring. So no difference there that I can see.