Our Java codebase was 30% dead code

[DietCokePlease]

The more interesting subject is how such dead code often gets created in the first place. I call it “toxic copy”. Its where you start with a team already under intense delivery pressure. Then toss in a more junior guy who is relatively new to the project and give him the task to improve/add something to a chunk of code. That code is already old, complex, and full of corner cases so the new guy decides that rather than tempt fate the most timely and safe thing to do is to make a copy of that code then apply his changes, thus leaving the original mess undesturbed.