Lecture 17
10/24
see nonoop examples

+ Reminder from last lecture

  public class MC {
     classvariables;
     classmethods;
  }

+ Methods and variables can go in any order
  - For style, put vars first then methods
  - For methods, put approximately in order called

+ examples: nonoop1,2,3

+ How to understand memory and access?
  -> SCOPE: portion of code from which variable/method can be accessed
  -> Use BOX DIAGRAMS
  -> boxes "carve" out portions of memory to store values
  -> represent both variables and methods with boxes
  -> boxes/values drawn/written at the location (space and time) a portion
     of code activates!

+ Scope (Box) Diagram rules
  (gradually updated as we introduce more language elements)

  . every class gets a box
  . every class variable gets a box inside the class box
    - default values of class variables are zeros
        what are zeros?
        $int$ has default of $0$
        $double$ has default of $0.0$
        $boolean$ has default of $false$
        (and more to come)
    - every time a value changes, cross off the old value and write the new one
      to the right (or nearby)
    - every class method gets a box inside the class box WHEN the method is
      activated
    - write the method header above the method box
  . local variables
    - each local variable gets a box
    - local variables have unknown/undetermined values,
      so write a question mark (?) inside the local-variable box

+ Methods: each time the method activates, cross off the method box
  and draw a new one to the right
  ACTIVATION RECORD: the final collection is a record of the 
                     times the method was called

+ example: nonoop4
+ see box diagram

+ why static?
  - no objects created yet
    class  = blue print
    object = specific instance created using class as template
  - static means can use code DIRECTLY from class without making objects
  - generally, bad style: use only when have extremely common information
  - good style: information hiding
    - move information far away from user
    - security
    - reliability of code
    - ease of reuse