1. Object Oriented Programming
Prototype based vs class based OOP
Prototype based OOP
- cloning, virtual and copied fields and methods
SELF
Problems: code is not shared, too dynamic

2. Class based OOP Classes vs instances Only classes have code
Only classes inherit
Instances have state variables
Variations in instances implemented as values of state variables.

3. Inheritance Type vs Implementation inheritance
Types: roles that an object can have -> INTERFACES
Organized as a DAG i.e. multiple inheritance for types is relatively trouble free.
Classes: implement code – single inheritance:
controls complexity
adds security

4. Accessibility of methods and variables in a class
Final
Ex: security manager
Public,private,protected,default
Absolute: public, private
Dependent on Packages: default, protected

5. Class vs instance (Static vs. dynamic) fields/vars and methods
Class variables: shared among all instance – visible to all instances
Ex: instance counter
Ex: security manager – final!

6. Inheriting Methods
Virtual methods – all java instance methods are virtual
Extra (hidden) parameter: this
search for an absent method or field always starts from the class associated with “this”
Ex: Circle extends Point -> hide(), show(), moveTo(x,y) – virtual, uses hide() and show() as defined based on the “this” parameter