| Critical | Security vulnerability, data loss risk, production crash | | High | Bug likely, significant performance issue, breaks API contract | | Medium | Code smell, maintainability issue, missing best practice | | Low | Style, minor optimization, suggestion |
| Null Safety | Chained calls, Optional misuse, null returns | | Exceptions | Empty catch, broad catch, lost stack trace | | Collections | Modification during iteration, stream vs loop | | Concurrency | Shared mutable state, check-then-act | | Idioms | equals/hashCode pair, toString, builders | | Resources | try-with-resources, connection leaks |
| API | Boolean params, null handling, validation | | Performance | String concat, regex in loop, N+1 |
Systematic code review for Java with null safety, exception handling, concurrency, and performance checks. Use when user says "review code", "check this PR", "code review", or before merging changes. Source: decebals/claude-code-java.