What are the benefits of dependency injection containers?

Question

I understand benefits of dependency injection itself. Let\'s take Spring for instance. I also understand benefits of other Spring featureslike AOP, helpers of different kind

Answer 1

Ease of combining partial configurations into a final complete configuration.

For example, in web applications, the model, view and controllers are typically specified in separate configuration files. Use the declarative approach, you can load, for example:

  UI-context.xml
  Model-context.xml
  Controller-context.xml

Or load with a different UI and a few extra controllers:

  AlternateUI-context.xml
  Model-context.xml
  Controller-context.xml
  ControllerAdditions-context.xml

To do the same in code requires an infrastructure for combining partial configurations. Not impossible to do in code, but certainly easier to do using an IoC framework.