This repostitory contains design-pattern examples used in the book Head First Design Patterns.

• Abstraction
• Encapsulation
• Polymorphism
• Inheritance

• Identify the aspects of your application that vary and separate them from what stays the same.
• Programm to an interface, not an implementation
• Favor composition over inheritance.

The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

• Freeman, E., Robson, E., Bates, B., & Sierra, K. (2008). Head first design patterns. " O'Reilly Media, Inc.".