CS51 - Spring 2010 - February 4

  • Extended discussion of problem 6.9.1 in the book

  • instance variables
  • keeps track of the state of an object
  • can be used in multiple methods

  • constructors
  • what does a new object "look" like?
  • at a minimum should initialize the instance variables.

  • parameters as a way of passing information
  • formal parameters in constructor/method declarations
  • scope is that constructor/method
  • actual parameters are passed in when that constructor/method is invoked.
  • what matters are that the types match (or can be converted, for example passing in an int when the method expects a double), and that the order is correct.

  • local variables
  • scope is only a single method (or constructor)
  • if something doesn't need to be an instance variable, don't make it one.

  • method overloading
  • two (or more) methods with same name, different signatures
  • convenient/good-style to have overloaded methods call each other if they do the same (or very similar) things

  • public vs. private
  • by default, instance variables should be private
  • methods can be public or private depending on what they're for
  • discussion of public vs. private constants

  • use of keyword this, both with methods and instance variables