New ask Hacker News story: Ask HN: What tools do you use to understand big code-base?

Ask HN: What tools do you use to understand big code-base?
3 by c3c | 4 comments on Hacker News.
You are given a big Java (or another language) project to contribute to. No documentation. How do you start? What tools do you use to understand the high-level structure of the code? Thanks HN!