hhdfsdThe project contains source code from the headFirst Design pattern book. I wrote it to refresh my Design pattern knowledge :) and trying to improvise stuff.

One of the visible examples in Java API of Strategy Pattern is - Collections.sort(List,Comparator) --> sort method is closed for modifications and Comparator method is open for extension thus algorithms are varying independent of the client that uses it.
test-
Observer Pattern - A easily recognizable implementation of observer pattern in the Java APIs is the EventListeners in the GUI APIs of Java.

Decorator pattern - Used for extending object's functionality at runtime, without the need to use inheritance. java.io.* is one of the examples of the Decorator pattern.