Summary:


1. Observer (action A causes action B to happen) (adding Observers to our concrete Observable class)

2. Iterator (returns each element in a collection in a certain order)(we do this from a separate class to de-clutter the class containing the collection)

3. Strategy (isolate different strategies/algorithms inside a separate class which can be included as a class variable inside the context)(instead of two objects with the same content except for different algorithms)

4. MVC (separates what the user sees (View) from the data being stored (Model) and the methods that interact with each (Controller))

5. Dependency Injection (creating instances of one class elsewhere and introducing them into our other class as an argument in the constructor and/or a method)

6.(a) Static Factory Method Pattern (has one factory method inside a factory class that can be instantiated anywhere, providing new instances of various subclasses)

6.(b) Factory Method Pattern (same as static Factory Method Pattern, but with more than one subclass of "ShapeFactory" or whatever your Factory name is)

Many patterns help us refactor code so that we extract code from class A, put it in class B, and store an instance of class B inside A. (#1 - remove the update() code, #2 - remove the next() and hasNext() methods, #3 - remove the algorithm)

To Use These:

- recognize a flaw that can be fixed with a pattern
- decide on the pattern
- figure out how to implement it