To Notes

CSC 212 -- 1/17/08

Review Questions

1. What is a UML diagram?

   Ans: A diagram that shows the following information: class name; for each instance variable, the datatype and accessibility (private or public); for each method, the signature, return type and accessibility.

2. What is the signature of a method?

   Ans: An ordered list of the datatypes of each parameter.

3. What does it mean to say that methods are overloaded?

   Ans: It means that those methods all have the same name but different signatures.

4. What is a primitive datatype?
   Ans: A datatype that is not defined by class. Java primitive types are byte, short, int, long, float, double, char, boolean.

5. Use the Character class to convert the char variable x to upper case. See the Week2 Character Example. Ans:

   char c = Character.toUpperCase(x);

6. How do you write a Java program to test a class?
   Ans: Write code to call each public method in the class, some more than once to cover all the cases defined within the method.

More Builtin Java Classes

• StringTokenizer Class   Abbreviated UML Diagram
  Code to test StringTokenizer class:   TestStringTokenizer.java

• Scanner Class   Abbreviated UML Diagram
  Code to test Scanner class:   TestScanner.java

Designing Your Own Classes

• An instance variable in a class represents a piece of data describing that object.

• The instance variables represent the state of the object.

• A method is a procedure that the class can execute to do something.

• Practice Problems:   Draw the UML diagram for these classes. Choose plausable instance variables and methods. For simplicity, use public instance variables and no getters or setters.
  BasketballPlayer   UML Diagram

  Coin   UML Diagram

• Methods tend to be public; instance variables tend to be private.

• For each private instance variable, use a pair of methods (a getter and a setter) to access the instance variable.

• For example, if the instance variable is width, the getter is called getWidth and the setter is called setWidth.

• To make the instance variable read only, only supply a getter method.

The Person Classes

• Look at the Week3 Person Examples.

• Note: the Person.java files are different for each example. Be sure to download the correct version depending on which test file you are using.

The Vehicle Class

• Design a class that represents a vehicle. You choose the instance variables. You can use strict getter and setter methods, or you can design the getters and setters to be more practical.
  1. Draw the UML diagram.

  2. Write the code for the Person class.

  3. Write code to test the Person class.

Project Proj3

• Look at the Project Proj3 Description.