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

Often, the important point is who is changing the configuration after the program was written. With configuration in code you implicitly assume that person changing it has the same skills and access to source code etc as the original author had.

In production systems it is very practical to extract some subset of settings (e.g. age in you example) to XML file and allow e.g. system administrator or support personal to change the value without giving them the full power over source code or other settings - or just to isolate them from complexities.