State machine observer in Java

ObserverConsole

The most basic observer is the console observer ObserverConsole which logs all messages to the standard output.

Here is how to use the ObserverConsole singleton class:

ObserverTrace

A powerful observer is ObserverTrace which uses the standard java logging system. it logs messages according to its configuratinon file. Messages can be sent to according to their level and towards many kind of destination: console, file, database etc ...