[mmcdermott]

In theory, I agree, but I don't think that holds terribly true in practice.

One of the ideas behind IoC frameworks (which build on top of DI) is that you could swap out implementation classes. For a great deal of software (and especially in cloud-hosted, SaaS style microservice architecture) the test stubs are the only other implementations that ever get injected.

Most code bases could ditch IoC if Java provided a language-level construct, even if that construct were only for the test harness.

[Jach]

Java has a mechanism, just pass alternate implemenations in constructors. If you must, a setter method. For most code you don't need to bring in the overhead of Spring, and @Autowired isn't really more convenient typing wise. Plus your unit tests become trivial, they're just POJOs with @Test annotations.

Spring is great when you need that dynamic control at runtime (especially when code dependencies are separated by modules) but you're just aping what good dynamic languages like Clojure or Common Lisp give you for free. But I can't complain too much, developing modern Java with its popular frameworks and with JRebel is getting closer to the Lisp experience every year, I'd rather have that than for Java to remain stagnate like in its 1.6/1.7 days.