Super-low hanging fruit: fix checkstyle violations, look at the latest build under
https://travis-ci.com/github/vassalengine/vassal (or build the master branch locally), fix the warnings that checkstyle spits out (currently whitespace). Once the current warnings are gone, we will turn them into build-breaking errors, and activate the next rules as warnings. There is still a lot to do in that area.
Other low-hanging fruit:
- get rid of compiler warnings (might be a bit tricky sometimes but some are quite easy to get rid of)
- write unit tests for simple classes (the ones that don't access anything static)
- find all the main() methods that are used for unit-testing, move that code into proper unit tests under src/test/java, just mark these unit tests with @Ignore so they are not executed automatically (IntelliJ has nice support for finding/creating unit tests for a given class, just press ctrl+T)
- error handling, find catch() blocks that do nothing or call e.printStackTrace(), change that to proper logging
I can explain these things in more detail if you are interested.