cs1302-ce09 More Shapes

十人十色 (Ten People, Ten Colors) --Japanese Idiom

This class exercise explores how to utilize inheritance in Java to create new classes that are directly based on existing ones, with an emphasis on code reuse and design implications. It also revisits how to commit and view changes to a local Git repository.

Prerequisite Knowledge

Course-Specific Learning Outcomes

LO3.b: Create class, interface, method, and inline documentation that satisfies a set of requirements.
LO3.c: Generate user-facing API documentation for a software solution.
LO4.c: (Partial) Design, create and use inheritance relationships in a software solution.
LO4.d: Utilize inheritance-based polymorphism in a software solution.

Questions

In your notes, clearly answer the following questions. These instructions assume that you are logged into the Odin server.

NOTE: If a step requires you to enter in a command, please provide in your notes the full command that you typed to make the related action happen. If context is necessary (e.g., the command depends on your present working directory), then please note that context as well.

Exercise Steps

Checkpoint 1 Steps - Getting Started

Use Git to clone the repository for this exercise onto Odin into a subdirectory called cs1302-ce09:
```
$ git clone --depth 1 https://github.com/cs1302uga/cs1302-ce09.git
```
[ALL GROUP MEMBERS] If you did not setup your Git username and email on Odin when working on cs1302-ce07, then please revist that exercise and follow the instructions presented there.
Change into the cs1302-ce09 directory that was just created and look around. There should be multiple Java files contained within the directory structure. To see a listing of all of the files under the src subdirectory, use the find command as follows:
```
$ find src
```
This is the same starter code from cs1302-ce08! Refer to your notes for that exercise about any inter-dependencies and/or inheritance between the files.
In your notes, draw a complete, proper UML diagram for the three classes contained in the starter code. You might need to devote an entire page to this. We recommend using a pencil. Refer to the CSCI 1302 UML Tutorial if needed. Specifically, each individual class diagram should contain:
- Class name;
- Variables;
- Constructors and methods;
- If needed, a solid generalization arrow (extends) to a parent class; and
- If needed, a dashed generalization arrow (implements) to an interface.
In a class diagram, do not list inherited members (methods or attributes) unless they are explicitly overriden. Be sure to include visibility modifiers (e.g., +, #, ~, -) and type / return type information where needed. Also, remember that generalization arrows have a triangle arrow head, which differentiates them from dependency and aggregration associations.

Checkpoint 2 Steps

Create and document a Rectangle class in the cs1302.shapes package. It should extend the Shape class. In addition to including relevant instance variables for describing a rectangle, it should provide a constructor and a set of overrides for the getArea and getPerimeter methods. Additionally, include getter methods for the instance variables.
Compile your Rectangle class. If you encounter any compililation errors:
1. Write the error down in your notes;
2. Fix the error in your code;
3. Recompile; then
4. Note the fix in your notes.
5. Repeat as needed.
Make sure that all Java files pass the checkstyle audit.
Since we've added a new class to our project, it's a good idea to save our work using Git. Check the status of your local copy of the repository using the following command:
```
$ git status
```
You should see a message similar to the following:
```
# On branch master
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#	src/cs1302/shapes/Rectangle.java
nothing added to commit but untracked files present (use "git add" to track)
```
As the message suggests, your Rectangle.java file is untracked. This is because it is a new file that is not currently tracked by Git. To have Git track changes on this file, use the git add command as described in the message.
Now, use Git to commit the changes that you made to your source code to your local copy of the repository. Remember to use the -m (message) option to give a brief, one sentence description of the changes you made to the source code. If you forget the -m option, then you Git will likely throw you into the Vi program to enter a message! 😱 Don't be scared if this happens to you... Press i, type your sentence, then press the intuitive sequence of keys: ESC, :, wq!, followed by return. Next time, remember the -m option.

NOTE: If you don't want to be inadvertantly thrown into Vi in the future, then add the following line to your ~/.bash_profile to set the default editor to Emacs (changes take effect on next login):
```
export EDITOR="emacs -nw"
```
Generate the API documentation website for all of the code in the cs1302 package into the doc directory. You may need to create the doc directory if it does not already exist. Host the documentation on Odin using cs1302-ce09-doc as the name for your symbolic link. Write the full URL for the Rectangle class in your notes.

Checkpoint 3 Steps

Create and document a Square class in the cs1302.shapes package. It should extend your Rectangle class. You shouldn't need to introduce any new instance variables, but you should include a constructor that makes proper use of the super keyword.
Compile your Square class. If you encounter any compililation errors:
1. Write the error down in your notes;
2. Fix the error in your code;
3. Recompile; then
4. Note the fix in your notes.
5. Repeat as needed.
Make sure that all Java files pass the checkstyle audit.
You just utilized inheritance to reduce the amount of code needed to create a new class! Your Square class has everything a Square has. How much new code did you need to write? Use wc to check your coder stats!
1. How many lines are in Rectangle.java?
2. How many lines are in Square.java?
Contrary to popular belief, fewer lines of code is usually better. Also, if you need to make a change to a Rectangle method, then this change will propogate throughout all descendants in your heirarchy that don't explicitly perform an override of the relevant method.
Tell Git to track changes made to your Square.java file, then commit the changes to your local copy of the repository. Be sure to include a good log message.
Generate the API documentation website for all of the code in the cs1302 package into the doc directory. You may need to create the doc directory if it does not already exist. Host the documentation on Odin using cs1302-ce09-doc as the name for your symbolic link. Write the full URL for the Square class in your notes.

Checkpoint 4 Steps

Create and document a ShapeDriver (driver) class in the cs1302.shapes package. Inside of the main method do the following:
1. Create a Shape array, and populate it with two objects of each class (so, 8 total). Something like the following (will need to be modified):
```
Shape[] shapes = new Shape[] {
    new Ellipse(1.1, 2.5), 
    new Circle(1.5)
};
```
2. Loop over the array. For each element in the array, print the name of the shape using the getName method as well as the return values of the getArea and getPerimeter methods. Which classes do not explicitly define getArea and getPerimeter?
Make sure that all Java files pass the checkstyle audit.
Compile the ShapeDriver class and run it. Is the output what you expected?
Tell Git to track changes made to your ShapeDriver.java file, then commit the changes to your local copy of the repository. Be sure to include a good log message.
Regenerate the API documentation website for all of the code in the cs1302 package. What is the direct URL to the API documentation for the class that you wrote for this checkpoint?
Use Git to view your commit log.

Submission Steps

Each student needs to individually submit their own work.

Create a plain text file called SUBMISSION.md directly inside the cs1302-ce09 directory with the following information.
1. Your name and UGA ID number;
2. Collaborator names, if any; and
3. The full link to the website generated in this exercise.
Here is an example of the contents of SUBMISSION.md.
```
1. Sally Smith (811-000-999)
2. Collaborators: Joe Allen, Stacie Mack
3. https://webwork.cs.uga.edu/~user/cs1302-ce09-doc
```
Change directories to the parent of cs1302-ce09 (e.g., cd .. from cs1302-ce09). If you would like to make a backup tar file, the instructions are in the submissions steps for ce02. We won't repeat those steps here and you can view them as optional.
Use the submit command to submit this exercise to csci-1302:
```
$ submit cs1302-ce09 csci-1302
```
Read the output of the submit command very carefully. If there is an error while submitting, then it will displayed in that output. Additionally, if successful, the submit command creates a new receipt file in the directory you submitted. The receipt file begins with rec and contains a detailed list of all files that were successfully submitted. Look through the contents of the rec file and always remember to keep that file in case there is an issue with your submission.

Note: You must be on Odin to submit.

Copyright © Michael E. Cotterell, Bradley J. Barnes, and the University of Georgia. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License to students and the public and licensed under a Creative Commons Attribution-NonCommercial 4.0 International License to instructors at institutions of higher education. The content and opinions expressed on this Web page do not necessarily reflect the views of nor are they endorsed by the University of Georgia or the University System of Georgia.

cs1302uga / cs1302-ce09