Which services would you recommend, and why?
We would like to avoid online training, and self taught video/tutorial series.
Looks like they offer Java 8 training. If I remember correctly onsite 5 day training cost 20k-25k for 10+ people who already have dev experience. Pricey but a lot cheaper than hiring a team of Java developers.
Feel free to email if you have any questions or happen to be located in the Chicago/New York/San Francisco area and want to talk about what we can offer. taylor@actualize.co
You might consider talking with either ThoughtWorks or Pivotal Labs. Both have deep Java expertise, but more importantly, the ability to have your team members work side by side with them on the other aspects of dev methodology.
Neither is inexpensive, but may be helpful if your team is trying to bridge more than just a Java knowledge gap.