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Troubleshooting

If you're having issues with Java, VS Code, running your files, or running unit tests, try the steps below and make sure you have everything correct!

Clean Java Workspace

First, try cleaning the Java workspace. This clears your projects and restarts VS Code.

Open the Command Palette with F1 or Ctrl+Shift+P (Cmd+Shift+P on Mac) and search for clean java. You'll want to select the Java: Clean Java Language Server Workspace option:

Clean Java

Next, in the lower-right corner, click Reload and delete:

Reload and delete

Common Issues

  1. Make sure the CS159 folder is open in VS Code

    • In VS Code, use the top menu to go to File > Open Folder... and then select the CS159 folder that you downloaded in Installing Java, VS Code.

    • You should see a single CS159 folder at the top of the explorer pane:

      CS159 Folder

    • There should be four folders underneath, .vscode, bin, lib, and src.

  2. Make sure your code is placed in appropriate folders under the src folder

    • Homework should go in individual hw1-hw8 folders inside the hws folder
    • Labs should go into labs, etc.

  3. Make sure your package statement matches the folder structure

    • e.g., if you have ExactChange.java in src/hws/hw2, the package should be hws.hw2.

      Package statement matches folder structure

    • Usually VS Code automatically inserts this line for you, but if you move files around, it could be incorrect.

  4. If you are unable to run a file, make sure that it is something you can run!

    Select main file

    • You can't "run" a file that doesn't contain a main method.
    • Don't create a main method unless the assignment asks for it. (Gradescope may not be happy if you do so)
    • Instead, you should be running your unit tests to check if your code works.

  5. If you get an error saying that the Update jacoco.xml task failed, or you are unable to display coverage:

    • Please check your Java version and make sure JDK 17 is installed (see section below)!

Uninstalling JDK

Check the version of Java you're on by opening a terminal or command prompt and running the command java -version.

Java version

If this shows a major version of 17 like in the screenshot above, you're good to go!

If this shows any other version (like 21), then you will need to uninstall the current JDK and install version 17.

  • On Windows:

    • In your Start Menu, open "Add or remove programs" or "Apps and features", then search for Temurin, JDK, or Java.

      Uninstalling JDK on Windows

    • Uninstall anything that is not version 17.

  • On Mac:

    • Open the Finder, then go to Macintosh HD > Library > Java > JavaVirtualMachines.
    • Delete any folders that are not version 17 (like temurin-21.jdk).

Next, follow the steps in Installing Java, VS Code to install version 17 of the JDK.

Important!

Afterwards, open VS Code and clean the Java workspace. You may have to wait a while for VS Code to re-open your projects and work with the new JDK version.