[Patrick Chiang]

We were trying to decide on whether to do the reverse thing for next year (switching from Java -> LV), so we did an informal survey of the teams at our regional this weekend. Surprisingly, out of 33 teams, 3 teams were using LV, 2 C++, and most of the rest Java. It blew my mind how popular Java has become since it was introduced less than a year before I came into FRC.

We have used both languages, and here is a comparison from my experience. IMO, they both have their merits but I personally prefer Java, so that's my bias.
Java:
+ Easier to find and solve fatal bugs. When program fails, Java tells you exactly where it does and what you need to do to solve that problem, sometimes even if you have never seen that error before. Code errors are easier to post onto Chief Delphi and stack overflow than screenshots of your LV wiring.
+ Faster deployment cycle. 52 seconds on ours to be exact, yes we counted. The 4 minute LV re-deployment on our laptop can be a major problem if we have to make even a minor change in the elimination rounds. LV is also a memory hog, which is ironic because a lot of traditional programmers consider Java a memory hog.
+ More intuitive for "software engineers". Lines of code and all. Taught in AP CS and college intro CS courses. I've heard that LV is more intuitive for EE people with its resemblance to circuit diagrams.
+ Source version control. In a good IDE, revert your code to what you had at 12:34 pm on May 6th, 2007. The "undo" function for LV is very limited, and you can't compare code differences on GitHub or something similar AFAIK.
+ Documentation. You can browse through Javadocs on a browser, whereas my experience with searching through LV functions is a nightmare-filled trip into a Windows Help style interface. In Java Netbeans, you can hit control+space and have it come up with every available function for a certain device, listed by contextual relevance.

LV:
+ Click and drag. How much easier does it get? If you know "line-based programming" before you learn LV though, it can be a nightmare.
+ Easier to tune specific functions (ex: PID). You can add a bunch of controls to the frontend without adding much code. Sometimes Java's Smart Dashboard just doesn't cut it.
+ More support at our FRC regionals. The control system advisor team is filled with NI people. For Java problems, be prepared to consult your neighboring Java gurus.
+ Easier to implement concurrency. You can easily do multiple things on the robot at the same time. On the other hand, you can easily do multiple things on the robot at the same time (which can be unintended). I heard some teams using the subsytems thing in Java have this pretty easy too, but have yet to try that.
+ Sample code. LV sample code for FRC beats out Java sample code hands down, especially in the vision department. It's been developed longer, and it just covers more.
+ Vision. LV is better for vision development hands down. The fastest way to develop vision code in Java is to do it in NI's software, then copy the filters back into Java. The simplicity of it all is really one of the best unmatched feature LV has over Java.

For a decision, as others have mentioned it may be important to consider what the mentors and team already know. However, both languages are easily learned, and the most important factor is by far the personalities of the programmers:

If you have hardcore software writing students who know every single shortcut key available on the computer by memory, think wiring and electrical are hardware problems, and have 4 different flavors of Linux installed on their home computer, making them do LabView is going to end up in disaster.
Actual quotes: "why the !#%$ are these being executed at the same time", "give me a break, I just copied and paste and now every wire is broken", "I hit the limit on the Undo button so we lost everything we did yesterday"

If you have hardcore electrical students who know what every number on their 8-function multimeter mean (yikes), can trace 6ft long PWM wires through spaces too small for adult hands, and dumpster dive for broken down lasers in their free time (all real life examples), Java may not be the best idea.
Actual quotes: "frigging red syntax errors everywhere", "why did it only work the first time", and my personal favorite "I think we fried Java"