CS51 - Fall 2009 - Lecture 13

  • More discussion of interfaces

  • Lab 5 - Frogger:
  • Description: <html> <pdf>

  • Article by Kirschenbaum on Why humanities students should learn to program. Hello Worlds

  • Object oriented design
  • Decomposing the world into objects
  • instance variables and constants represent properties
  • methods represent behaviors

  • A few things to think about
  • how accurately do you want to model reality?
  • are there instance variables / methods that you need that aren't for modelling reality, but which are necessary to get the code to work?
  • getters/setters?

  • Design of Frogger
  • What are the classes? What objects appear in the game?
  • Frog
  • Highway
  • Cars, trucks, etc
  • What are the properties of a frog? The behaviors?
  • location, appearance, whether it's alive
  • moving, dying, being reincarnated
  • What are the properties of a vehicle? The behaviors?
  • Note that frog and cars need to know about each other (note resemblance to Ball and Box classes from last lab)
  • What are the properties of a lane? The behaviors?
  • Think about how Lane and Vehicle resemble Tree and FallingLeaf from example in earlier lecture.
  • Note that this is not complete! Quite common to do initial design of a class and then to realize later than you need to add a little more to it, or to change it somehow, in order to get the overall program to work.