Autowiring static member via components constructor

Question

I know this compiles, but my question is, is it a good idea? I'm mostly curious about why it might NOT be a good idea. Even better, is there an alternative, if SomeStaticClass is a @Component, but it also must be a static member of MyComponent. My understanding is that its poor design to have Spring autowire static members. Based on what I've read, I still don't quite understand why. Say I have the following:

@Component
public final class MyComponent {

  private static SomeStaticClass someStaticClass;

  @Autowired
  MyComponent(SomeStaticClass someStaticClass) {
    MyComponent.someStaticClass = someStaticClass;
  }

}

Answer 1

Few reasons why it's a bad design:

• static mutable fields are a bad design in general

• makes testing harder - once this field is set, it will remain set in the next test, possibly creating hidden interdependency

• what if you want to have two instances of MyComponent, each with different SomeStaticClass? Chaos.

• you cannot inject values via static field or setter autowiring, it's explicitly forbidden. There must be a reason for that.

• why do you even need that? Do you have static methods in MyComponent? Why?

• if the above is true, how do you prevent calling MyComponent.staticMethod() before the constructor initialized that field? The whole point of Spring is to return fully populated, safe beans