Eclipse and JUnit

In this lab, you will explore Eclipse. If you already use the Eclipse editor, this lab, may provide you with more information.

All Eclipse applications are built as a project. Each lab and each PA that you do this semester should be in its own project and each project will have its own folder.

Part 1 - Hello World

  1. If you have not done so already, open Eclipse. At the "Workspace" prompt, fill in your workspace. This could be a folder on a thumb drive or your desktop.
  2. Choose the tutorials icon. (Pen and green checkbox).
  3. Choose "Create a Hello World application".
  4. Follow the steps in the tutorial. Be sure to see how the automatic syntax checking works by introducing some bugs. Also explore the autofill options (showing the list of available members of an object).

Part 2 - Importing Preferences

  1. Download CS159_formatter_V1.xml from the course Supplemental Material page.
  2. Follow the instructions on that page to import the file into Eclipse.
  3. Test the auto-format feature by selecting some code in your Hello World project and pressing Shift+Ctrl+F. You can also find the auto-format option under the Source menu.

Part 3 - Import other .java files into a project

Next, you will practice downloading existing java source files and importing them into your project.

  1. Download the files Point.java, PointUtils.java, and PointDemo.java to your Desktop.
  2. Drag those file into the "src" section of your project.

    At this point you should see some red x's indicating that there are errors in your newly imported files. We'll deal with that in the next section.

    Note that you can also import .java files using the "File" menu. You should NEVER mess with files in your Eclipse workspace using an external file manager. Always add or remove files through the Eclipse interface.

  3. Take a few minutes to figure out what PointDemo.java is supposed to accomplish. At this point the class PointDisplay is missing, but you can see its javadoc here: PointDisplay.html.

Part 4 - Adding .class files to a project

Sometimes it may be necessary to include a pre-built java .class file in your project.

  1. Download the files PointDisplay.class and PointDisplay$PointCanvas.class to your Desktop.
  2. Go to "Project / Properties" and click on "Java Build Path".
  3. Click on "Libraries" -> "Add Class Folder" -> "New Folder". Give your folder a name such as "classes".
  4. Press "Okay". You will see a new section in the Package Explorer window called "Referenced Libraries" and you should see your new folder beneath it.
  5. In the Eclipse window, drag and drop your .class files into the folder you just created. All red x's should disappear.
  6. Run PointDemo.java to confirm that everything is working as expected.

Part 5 - JUnit testing

JUnit testing is supported by Eclipse. For this part of the lab, we'll use Eclipse to build JUnit tests for for the PointUtils class. This class does contain at least one error. Don't fix any errors. Your goal for this stage of the lab is to write JUnit tests that catch errors in the existing code.

  1. To create a new JUnit test for a particular file in the project, right click on the name of the file in the "src" list and choose "New / JUnit Test Case".
  2. Click on the "JUnit 4" Test radio button.
  3. The name of the file defaults to the name of the active class with Test appended (PointUtilTest).
  4. Click on "Generate comments", and then click on "Next".
  5. From the list of methods of the PointUtil class, click on the box beside each of the two methods in the class. Don't worry about the Object class below it.
  6. Click "Finish".
  7. Implement JUnit tests for the two methods in PointUtil. Adequate testing will probably require more than just two test methods.
  8. Run your tests by right-clicking PointUtilsTest and selecting "Run as" -> "JUnit Test".
  9. If your tests are implemented correctly, at least one should fail. Try fixing PointUtils.java to confirm that it passes your tests after any errors are corrected.
  10. Submit your completed PointUtilsTest.java through Canvas. Your grade on this lab will be based on this submission.

Part 6 - CodingBat

If you have not already done so (last semester) go to CodingBat.com and set up an account. Once you have an account, you can add your instructor by going to Prefs and then adding your teacher's e-mail address (spragunr@jmu.edu). If you already have a previous teacher listed, you can remove them now.

Do the problem in Warm-Up 2 called frontTimes (http://codingbat.com/prob/p101475).

This is a modified version of a lab designed by Michael Norton and Nancy Harris.