Closures vs Lambdas

Where closures go beyond lambdas is that they bind or "close over" variables that are not explicitly defined in the closure's scope.

http://dublintech.blogspot.com/2014/05/groovy-closures-this-owner-delegate.html

Use lots of small simple classes instead of big complex classes

Favor complex network of simple objects over a simple network of complex objects

http://stackoverflow.com/a/2947823

That's one more voice in favor of the "tiny pieces" method of breaking down applications.

When to use 'new'

Now, this isn't to say that you can never use new manually -- but you should reserve that for value-type objects that don't have external dependencies. (And in those cases, I'd argue that you're often better off with a static factory method than a public constructor anyway, but that's beside the point.)

http://stackoverflow.com/a/28749192

Why not to use PowerMock

In my opionion [sic], creating a new collaborating service is not bad primarily because it's untestable, but because it introduces coupling and undermines polymorphism, and similarly for the static invocations of the Database class. 

 http://blog.xebia.com/mocking-the-unmockable-too-much-of-a-good-thing/

So "testability" has always been more than just whether a class is literally testable in terms of lack of technical limitations. Author seems to suggest "testability" has really been a proxy argument for good OOP design.

Having realized this, I now understand what Misko Hevery meant when he said the following (unfortunately without elaborating):

 Yes I am aware of them, and I think it is a bad idea. You are trying to compensate bad design with Monkey Patching.

http://misko.hevery.com/2008/12/15/static-methods-are-death-to-testability/

APIs should be impossible to misuse

It should hard or impossible to misuse a good API

Josh Block
https://www.youtube.com/watch?v=aAb7hSCtvGw

The above statement validates my preference for using the Builder Pattern to facilitate clients to provide named constructor arguments in a sense. E.g. if a constructor has several string parameters, rather than rely on flaky javadocs and parameter names to inform the user what to provide, I would prefer to provide builder methods that unambiguously let the user know what to provide. For validation of inputs, I make the null checks, etc, in the private constructor. That makes it about as hard to misuse the API/constructor as possible in Java.

Constructor Parameters known only at Runtime

it's assumed here that your Factory knows what the parameters for the constructors should be. If this is only known by the client of the Create method, then I would say the indirection isn't necessary and the client should construct the rule itself

http://stackoverflow.com/a/23765599

So, Factory Pattern may not be appropriate when the constructor parameters need to be provided by the client.

As for "DI abuse," see http://stackoverflow.com/a/1056229 on direct instantiation rather than injection of stateless services:

The abuse of DI leads to stateless objects which really should be stateful ... such code is by nature domain/use-case specific. In such a case ... it makes much more sense to have the [client] directly instantiate the business service class, passing data provided by the user through a constructor

Abstract Factory and "DI Explosion"

On the problem of creating objects from both stateless services and runtime values, Mark Seemann suggests the standard Abstract Factory pattern while seeming to acknowledge that it may be overkill for simple cases (i.e. say we have a lot of these objects to create, e.g. subclasses of say HystrixCommand, do we really want to create a Factory implementation for each subclass?)

Yes I know this, though in my case I hesitate because for simple cases it's overkill to duplicate constructor with interface, factory, factory's constructor, Create method, etc. While good for complex cases, it's too "DI explosion" for simple things I think. And the question remains about automatic registration DI container. – queen3 Nov 6 '09 at 11:16 @queen3: I understand what you mean, but I'm not aware of any DI Containers that can do what you ask.

http://stackoverflow.com/questions/1686760/which-di-container-will-satisfy-this/1686887#1686887