Lecture 7: Example: CreditCard class; UML class diagrams

lecture video

Textbook section

1.7

An example program: CreditCard

Build your programs one step at a time!

Demonstrates many of the things we’ve learned so far:

• modifiers (private, public, static)
• instance variables
• constructors
• methods
• the this keyword

The main method also demonstrates:

• an array
• a while loop
• a for loop
• a for each loop
• making calls to “normal” (nonstatic) methods
• making calls to static methods

UML diagrams

A UML diagram gives the name, attributes, and methods of a class, along with their visibility.

The first 3 minutes, 45 seconds of this video give a nice overview. (The rest of the video goes into inheritance, which we will cover next week.)

Files used in class

• CreditCard.java
• CreditCardDemo.java
• UML_class.pdf

Additional exercises

• R-1.11 from book: Modify the CreditCard class to include a method that updates the credit limit.
• R-1.12 from book: Modify the CreditCard class so that it ignores any request to process a negative payment amount.