Systematic approaches to reduce null pointer exceptions in legacy Java code

[Grace_T]

I'm working on a large legacy Java application where null pointer exceptions are our most frequent and frustrating runtime error, often buried deep in call chains and only surfacing in production under specific data conditions. We've tried adding defensive null checks everywhere, but it's making the code verbose and harder to read, and we still miss cases. For developers who have tackled this in mature codebases, what systematic approaches or tools have you adopted beyond manual checks? I'm interested in strategies like using Optional more effectively, enforcing nullability annotations with static analysis tools, or implementing a dedicated null object pattern for certain domains, and whether you found these techniques significantly reduced debugging time versus just adding more conditional logic.