Dependency Injection (DI) vs Service Locator Pattern?

Both decouple classes from their dependencies, but DI pushes dependencies in, while Service Locator pulls dependencies out.

In DI, dependencies are explicitly declared in the constructor. In Service Locator, the class explicitly asks a global locator registry for its dependencies. Service Locator hides dependencies (making code hard to test and reason about) and is largely considered an anti-pattern today.