Class 05: Lab: Objects and Methods, Continued

Held Friday, September 1, 2000

Summary

Today we continue our investigation of classes in Java through further experimentatino.

Notes

• Assignment:
  • Read lab J3
  • Work on HW1
  • Read Chapter 1 (The Object-Oriented Model) of Bailey
• Nathan has chosen office hours. He'll be in the MathLAN to answer CSC152 questions on Sundays from 6-8 and Mondays from 8-10.
• I've removed some parts from HW1. It is still due Tuesday.
• The Intro to Linux handout is not yet ready. I'm hoping to have it ready for Monday.

Overview

• On kinds of classes
• Lab
  • Questions
  • Work
  • Reflection

Lab J2, Continued

The Three Kinds of Classes

• Although I haven't mentioned it explicitly, Java programmers use classes for a number of reasons. I typically classify them as template classes, main classes, and utility classes.
• Template classes provide templates for creating new objects. Our Point and Fraction classes are template classes.
  • Template classes are the most common classes.
• Main classes provide a main method. You can think of the main method as a combination of the script and directory of a play. This method creates the objects that form the initial ``actors'' of the play that is your program. It then tells them what to do.
• Utility classes (which you haven't really encountered yet) provide methods for manipulating other objects. These methods are primarily class/static methods.
• Some classes are a hybrid of these kinds of classes.

Preparation

Are there questions on the lab?

Work

Continue working on lab J2.

Reflection

We'll stop about ten minutes early to reflect on what we've learned.