👀 Views: 380 💬 Answers: 1 📅 Created: 2025-09-06

refactoring legacy-code design-patterns unit-testing Java

I need some guidance on I'm converting an old project and I've searched everywhere and can't find a clear answer..... Quick question that's been bugging me - While refactoring legacy Java code, I stumbled upon a significant challenge involving the misuse of static methods within an inheritance hierarchy. The original design uses a `BaseService` class with several static utility methods that child classes are calling directly. For instance, the following code snippet illustrates the structure: ```java public class BaseService { public static String getConfigValue(String key) { // reads configuration return "value"; } } public class UserService extends BaseService { public void printConfig() { System.out.println(getConfigValue("user.config")); } } } ``` In this scenario, the `getConfigValue` method essentially functions as a globally accessible utility, but it introduces tight coupling and makes unit testing cumbersome. When writing tests for the `UserService`, I find it challenging to mock `BaseService` since static methods can't be easily overridden. I've attempted to refactor this by converting the static method into an instance method and injecting `BaseService` as a dependency into `UserService`. ```java public class BaseService { public String getConfigValue(String key) { return "value"; } } public class UserService { private final BaseService baseService; public UserService(BaseService baseService) { this.baseService = baseService; } public void printConfig() { System.out.println(baseService.getConfigValue("user.config")); } } } ``` However, this has led to a cascade of changes across several classes that rely on static calls, resulting in a convoluted refactoring process. Notably, I’m concerned about the performance implications of creating numerous instances of `BaseService`, especially given that it's designed to access frequently used configurations. Has anyone tackled similar challenges when refactoring legacy Java code with static method calls? What strategies did you use to not only smooth the transition but also mitigate performance issues? Any insights into best practices or design patterns that could help streamline this process would be greatly appreciated. For context: I'm using Java on Linux. Has anyone else encountered this? I'd really appreciate any guidance on this. For context: I'm using Java on macOS. Is there a better approach? My team is using Java for this microservice. Thanks for taking the time to read this!