There are reasons to not like Java, but this isn't one of them. Java is a fantastic language for large long lasting projects. I can't think of a more suited language for large long lasting projects in fact.
I mean if you like Java that's fine, to each their own I guess. But the thing that makes a codebase nice to maintain or not is how nice the code are is, nothing to do with language. If you try hard can you make a bit Java codebase easy to maintain? Probably. If you go in to maintain a random big Java codebase will you have a good time? No.
