CIS 180: Object-Oriented Programming
Homework #2

Objectives

• To practice designing a simple Java class for objects that represent temperatures and can convert temperatures from degrees Fahrenheit to degrees Celsius.
• To translate the design into a working Java program
• To compile, run and test the Java program

Problem Statement

Design and implement a class for Temperature objects that are capable of reporting their temperature in either Fahrenheit or Celsius. A formula for converting Fahrenheit to Celsius is:   C = (5*(F-32)/9)

The class should have one field (attribute) called degreesF, which contains the Fahrenheit temperature, and public methods called getFahrenheit(), which returns the temperature in Fahrenheit, and getCelsius(), which returns the temperature in Celsius. There should also be a public constructor method that takes the Fahrenheit temperature as a parameter.

Test your class definition by implementing a main() method that creates Temperature instances and displays their temperature values. Your program should produce something like the following output in the Java console:

The Fahrenheit temperature of thermometer1 is 20.0 degrees.
The Celsius temperature of thermometer1 is -6.67 degrees.
    
The Fahrenheit temperature of thermometer2 is 98.6 degrees.
The Celsius temperature of thermometer2 is 37.0 degrees.

You can use different values than the ones shown to test your program if you like. Also, don't worry about the exact format of the numbers. It is OK if your output displays a different number of decimal places.

Problem Decomposition

This problem can be solved using only one class, the Temperature class, which will implement the temperature conversion. It will contain a main() method in which Temperature instances will be created and used.

Design

• Step 1. Draw a UML class diagram to describe the design of the Temperature class. Your design should identify the name of the class, its attributes (fields) and behaviors (methods). Designate which elements will be private and which parts of the class will be public.
• Step 2. Create an eclipse project for this assignment and add a new class called Temperature. When creating the class, check the box to indicate you want eclipse to include a main method.
• Step 3. Type a multi-line Java comment block at the beginning of the Temperature.java file. The comment will serve as documentation for the program. A multi-line comment in Java begins with /* and ends with */ It can extend over multiple lines. Your comment should include the name of the class, the author (your name), and a description of the purpose of the class.

   /*
    *   Class Name: Temperature
    *   Author: (your name here)
    * 
    *   Description:
    *      (Describe the purpose of the class here.
    *       Use multiple lines, if necessary.)
    *
    */
  

Implementation

• Step 4. Use the stepwise refinement approach to code and test the Temperature class. Here's a sequence of appropriate steps, after each of which you should compile and run your program:

  1. Code the initial comment block.
  2. Code the definitions of the class's fields as well as the constructor method.
  3. Code a "stub" version (no code inside the curly braces) of the main() method if you did not have eclipse generate it for you in step 2.
  4. Code the definition for each remaining method, one at a time. Each time you add a method, add code to the main method to test it.
  • Add code to the main method to create and use one Temperature object. Write one access method at a time along with code in main() that tests the method. Here is where you would use print and println() statements to display the temperature values.
  5. Add code to the main method to create and use a second Temperature object.

Extra Credit

Read the From the Java Library Section of Chapter 2 of Java, Java, Java, 3E (pp. 91-94), and then incorporate code into your main() method that allows the user to input the values for temperatures. Follow the examples in the book of inputting numbers using the Scanner class. The input values read in main should be passed to the constructor method of the Temperature class.

What to turn in

When your assignment is complete, add some comments to the beginning of the java source code explaining any problems you encountered in completing the assignment and describing any bugs in your solution. Undocumented bugs are worse than documented bugs. If you have undocumented bugs we will assume that you did an inadequate job of testing your code, and you will lose additional points.

There will be a 10% penalty for assignments received after the due date. Assignments will not be accepted more than one week past the due date.