The final Keyword

Variables can be marked final, in which case that variable cannot be re-assigned. Finality is a property of variables; objects have no idea if a variable pointing at them is final. So, a final variable can be used to tell an object to change its state.

Constness Finality of variable + (primitiveness or immutibility of data) → constness.

Ideentifiers for constaants are all-caps.

The static Keyword

A class is divided into to parts, instance land and static land. The static etiquette rule applies: Things in Instance Land have access to things in Static Land. However things in Static Land do not have direct access to things in Instane Land.

Notice the grease on the static side of the wall and the ladder-rungs on the instance side.

Instance land consists of things that can vary from one instance of the class to another. Static land consists of things that are the same for all instances of the class.

    Instance Land        -|G        Static Land
                         -|R
                         -|E
    non-static (instance)-|A    static methods
    methods              -|S    static data and
                         -|E        constants
    state variables      -|
       and non-static    -|
       constants         -|
   ------------------------------------------------                        

when you make a class the class loader loads it into memory.
A static area of memory is set aside for static items in the class
All instances of the class can see it.  Things that are static
are accessed via the class name. 

• access specifiers: public, private
• final (applies to variables)
• static (applies to variables or methods)