'var' in C# and Java doesn't change strong or static typing at all. It's just type inference. Your code is still statically typed, the compiler and IDE will catch errors. It's just that it's smart enough to infer the types of redundant things instead of making you type it.

So instead of typing:

  AbstractConcreteFactoryFactory factory = new AbstractConcreteFactoryFactory();

You can just type it only once:

  var factory = new AbstractConcreteFactoryFactory();