Class 21: Pause for Breath

Held: Friday, 30 September 2005

Summary: Today we pause to consider what issues need review and to explore polymorphism in more depth.

Related Pages:

• EBoard.
• Reading on Polymorphism.
• Polymorphism Lab.

Assignments

• Homework 3: Composing Text.

Due

• Exam 1: Java Basics.

Notes:

• Have a great weekend!
• No reading for Monday.

Overview:

• Pause for review.
• Review of polymorphism.
• Polymorphic I/O.
• Lab.

The First Pause

• Now that you've survived the first exam, are there particular topics we've covered for which you need more explanation?

• Polymorphism permits us to write methods that can accept a variety of related parameters.
• It also permits us to write classes that build upon a variety of related classes.
• For example, a PrintWriter adds facilities to any kind of Writer.
  • Writers provide basic output; PrintWriters add the ability to print a wide variety of types.
  • We've already seen that PrintWriters can print to files or to the screen.
  • We'll explore some other interesting implications of this in class, particularly with regards to the StringWriter class.
• We've also explored these issues with regards to the layout experiments.

Lab Continued (and Beyond)

• Continue the polymorphism lab.
• When you finish that lab, begin Homework 3.