java-solidlisted

Review the provided Java code for SOLID principles violations. For each principle, check for violations and suggest targeted improvements. Tailor suggestions to the detected Java version. ## S — Single Responsibility Principle A class should have one reason to change. **Violations to flag:** - Classes named `*Manager`, `*Helper`, `*Utils` with more than 3 unrelated methods - Service classes that also contain validation logic, email sending, AND database calls - Classes with more than ~200 lines (often a signal of multiple responsibilities) - Methods that do multiple distinct things (parse + validate + persist + notify) **Fix pattern:** Extract each responsibility into its own class. Show the split. ## O — Open/Closed Principle Open for extension, closed for modification. **Violations to flag:** - `if/else` or `switch` chains on type/status that would require modification to add new types - Hard-coded behaviour that should be configurable - Direct instantiation of concrete classes in business logic (use interfaces) **Fix pattern:** Introduce Strategy, Template Method, or polymorphism. Show the refactoring. ## L — Liskov Substitution Principle Subtypes must be substitutable for their base types. **Violations to flag:** - Subclass overrides a method by throwing `UnsupportedOperationException` - Subclass weakens preconditions (accepts nulls when parent doesn't) - Subclass strengthens postconditions (returns more restricted type) - Square extends Rectangle anti-pattern **