CMPS 144L Temperature Lab

CMPS 144L Spring 2020
Lab #1: Preliminaries and the Temperature Class

Activity #1: Preliminaries

Before you get started on the "real" work of this lab, there are a few preliminary steps to take care of. If necessary, your lab instructor will help you through these.

Register for the Lab and Lecture parts of the course

Go to the CMPS 144L course web page

Click on Student File Submission System near top of page

Click on Register

In the box under Enter your ID Number, type in your Royal Number, including the leading upper case 'R' and click on Submit.

Enter a password, twice. It must be a "strong" password, meaning one that has length at least eight, includes a lower case letter, an upper case letter, a digit (0..9), and a character in none of those categories (e.g., $, #, &). It is vital that you remember your password, as you will need it throughout the semester.
As for the rest of the data that you can fill into the text boxes, all of it is optional.

After you've registered, verify that you can log in. (Click on the Log in link and then, on the page that appears, enter your login ID and password in the two text boxes (login ID on the left, password on the right).) Note that your login ID is not your Royal Number but rather the prefix of your U of Scranton e-mail address up to but not including the @ symbol. Thus, for example, if your name were Gourdhead Rumplestiltskin, your login ID might be gourdhead.rumplestiltskin.

Having registered for CMPS 144L, do the same for CMPS 144, the lecture part of the course. To do that, first go to the CMPS 144 course web page, click on Student File Submission System and then on the Register link. As before, enter your Royal Number. At this point, you should get the message Prior registration bound to this context!, which means that you have successfully registered for both the lab and lecture parts of the course and your login ID and password are the same for both.

Install Java SE and jGrasp

In order to do Java programming on your computer, it must have Jave SE (Standard Edition) installed on it. If you don't already have that (e.g., from when you took CMPS 134), you should do install it now. Version 8 (or later) would be fine.

There are a variety of "integrated development environments" (IDEs) intended to provide support to a programmer (to make the task of programming as easy as possible). The one that we encourage students to use in the first couple of CMPS courses is jGrasp. If your computer doesn't already have it (e.g. from when you took CMPS 134), you are encouraged to install it. Use the link in the previous sentence to get to the jGrasp website.

Activity #2: Complete the Temperature Class

This lab activity is intended to reacquaint you with object-oriented programming in Java. Specifically, you are to download an incomplete version of the Temperature class and to complete it. The bodies of one constructor and five methods are missing, each one having been replaced by the comment STUB!. Before trying to develop your own code for the stubbed methods, study the code that is already there, as it should give you a model to mimic. In particular, take note of the methods that are provided and make use of them, as appropriate, when completing the stubbed methods.

Enter an initial temperature reading, which should be a number optionally followed by C or F: -5C Calling Temperature(-5.000000,true) toString() yields -5.0C toString(true) yields -5.0C toString(false) yields 23.0F Enter command (H for help): M +18F Calling modifyBy(18.000000,false) toString() yields 5.0C toString(true) yields 5.0C toString(false) yields 41.0F Enter command (H for help): S 45 Calling setTo(45.000000) toString() yields 45.0C toString(true) yields 45.0C toString(false) yields 113.0F Enter command (H for help): D 68F Computing difference between 45.0C (113.0F) and 20.0C (68.0F) difference(20.0C, true) yields 25.000000 difference(20.0C, false) yields 45.000000 difference(20.0C) yields 25.000000 toString() yields 45.0C toString(true) yields 45.0C toString(false) yields 113.0F Enter command (H for help): Q Goodbye.

You are not to change the signature¹ of any of the public methods, or to add any public methods.

To test your work, you are expected to make use of jGrasp's Workbench feature and/or the TemperatureTester application. An example of a user/program dialog with that application is shown to the right, with input entered by the user shown in boldface.

The application begins by inviting the user to enter an initial temperature value, which is specified by a numeral optionally followed by either C or F (to indicate Celsius or Fahrenheit, respectively). (The default is Celsius.)

Thereafter, the user is expected to enter commands, each of which indicates either that the temperature is to be

modified by a specified number of degrees,
set to a specified number of degrees, or
compared to a specified temperature (to determine the difference between them).

Each command begins with a one-letter code —M for Modify, S for Set, or D for Difference— followed by a numeral and then, optionally, either C or F (to indicate Celsius or Fahrenheit, respectively). The Q command causes the program to terminate. The H command causes a few example commands to be displayed.

Not surprisingly, these commands are translated by the application into calls to methods in the Temperature class, namely modifyBy(), setTo, and difference().

When you are confident that you have completed the class so that each of its methods fulfills its specification, use the Student File Submission System to submit the source code file into the "Lab #1" folder. (See the link to it near the top of the CMPS 144L course web page.) Your lab instructor will assist you, if necessary.

One of your goals should be to complete the class without introducing any assignments to the instance variable. That is, the only method that should include a statement of the form celsiusDeg = X (where X is some expression) is the version of setTo() that was provided to you.

Another goal should be to re-use code wherever possible, rather than repeating code. For example, if two methods have similar purposes but one of them is specific to a particular temperature scale (e.g., Celsius) and the other method handles either scale, one of those methods should call the other one. (For a good example of this, see how the argument-less version of toString() calls the one-argument version. A similar relationship holds between the two versions of setTo().)

A third goal is to make use of the provided private methods. Calls to private methods would be appropriate in the degreesFahrenheit() method and at least one of the modifyBy() methods.

Footnote