IntelliJ is an IDE (Integrated Development Environment). It’s like a text editor (like Atom or Sublime) but it’s full of extra features which make developing large programs much easier.


  1. Java 10, from Lab 1 Setup.
  2. You have successfully created your local repo for the class on your own machine. This is the su19-USERNAME repository you made in Lab 1.
  3. You have pulled from the skeleton, and you have a lab4 directory in the same directory as your lab assignment folders.

Be mentally prepared to use a real world software development package. It will seem very complicated for a while, but we’ll lead you down the narrow path to success. Ask for help if you are stuck! It can be very hard to guess the right thing to do in IntelliJ.

Install IntelliJ

If you’re working on the lab computers, skip these steps. Otherwise, do the following:

  1. Install the Community Edition of IntelliJ from the JetBrains website.
  2. Download the appropriate version of IntelliJ for your operating system.
  3. Run the install file and follow the prompts to install IntelliJ onto your computer. Choose all the default settings.

While you’re waiting for IntelliJ to install (or, in the case of the lab computers, to start up), work through the Discussion: Mystery problem from lab 4 with your your partner.

Install the CS 61B Plugin

Begin the setup process by starting up IntelliJ. If you’re on one of the lab computers, use the command /share/instsww/bin/ in a terminal window to start IntelliJ.

Then follow the steps below.

  1. In the Welcome window, click the Configure -> Plugin button on the bottom right of the window.

    Configure Plugin

  2. Click the button labeled Browse Repositories… on the bottom.

    Browse Repositories

  3. In the window that appears, search for “CS 61B”. Install the CS 61B plugin.

    Browse Repositories

  4. After installation, Restart IntelliJ IDEA to finalize the installation.

For more information on using the plugin, read the plugin guide. You don’t need to read this now.

Project Setup

In order to run your files in this special environment where we can work our IDE magic, we need to import our files into a project, similar to how you might import images or clips into a project for a program like iMovie or Windows Movie Maker. Fortunately, this is a fairly painless process.

Every new assignment needs to be imported into IntelliJ.

Begin the setup process by starting up IntelliJ. If you’re on one of the lab computers, use the command /share/instsww/bin/ in a terminal window to start IntelliJ. Then follow the steps below.

  1. Upon opening IntelliJ, Import Project.

    IntelliJ Start Menu

  2. Find and choose your lab4 directory, then press the OK button. From here on out, you should be able to simply select next for every screen but to be safe, more screenshots follow.

    IntelliJ Select Folder

    • Make sure Create project from existing sources is selected and press next. You shouldn’t have to change anything at this step.

      Import Project

    • Leave these fields untouched and press next.

      Project Name

    • Do nothing here and press next. For context, IntelliJ is automagically detecting what your Java files are and self-configuring itself to edit and run them.

      Import Sources

    • You may not actually see this next window pop up. If it does, click Next. If it doesn’t, that’s fine.

      Import Sources

    • You may not actually see this next window pop up. If it does, click Next. If it doesn’t, that’s fine.

      Import Sources

    • You may not actually see this next window pop up. If it does, and you see 10.0 on the left sidebar, you’re in the clear and can simply press Next then click finish on the final screen and voila, you’re ready to start working on the assignment!

    Select SDK

If you keep clicking next without paying attention and get to a point where you see a message that says No SDK specified, stop! If you do NOT see 10.0 (or whatever version of Java you have installed), click the plus in the upper left corner and click JDK from the drop-down menu.


Find where your JDK is saved, select it, and press the OK button. You can run /usr/libexec/java_home on your terminal to find out:

$ /usr/libexec/java_home

If you’re on Windows, your path may look like C:\Program Files\Java\jdk10.0.1.

If you’re on a lab computer, it should be at /usr/lib/jvm/java-10-oracle/. Once this window closes and your screen looks like the last correct image above, press Next, then Finish, and you’re done!

Once you’ve pressed finish, you should see something really similar to the following image. You may need to click the little triangle next to lab4 in the top left to get the source files ( and for lab4 to show up. If you don’t see the sidebar, go to View -> Tool Windows -> Project.

Select JDK

These instructions apply for both initial setup and for future assignments. When you run git pull skeleton master to retrieve a new assignment and you notice that you have a new assignment directory, simply run through these steps again from 1 to 8. This will likely involve pressing next for all steps and, if IntelliJ asks you to overwrite various housekeeping files (such as .iml files) because they already exist, respond “Yes” or “Overwite” to those popup windows. This is so IntelliJ can automatically mark the new directories for your assignment to work with IntelliJ for you as opposed to you manually marking directories as source folders and/or modules.

Every new assignment needs to be imported into IntelliJ. Every single new lab and project needs to be imported into IntelliJ using this process. Yes, every single lab, and every single project needs to be imported the very first time.

Relax for a Bit

The first time you start up IntelliJ it’s going to spend some time indexing files. This may take a few minutes. There should be a little progress bar in the bottom right. Once it’s done, a sidebar will appear.

Continue working on the Discussion: Mystery question.

Setting Up Java Libraries

Remember the empty library-su19 folder? We are going to populate that folder with the Java libraries we need for this class.

  1. First, open up a terminal window and cd into your repository.
  2. Run

    git submodule update --init

    You should get output like this:

    Submodule 'library-su19' ( registered for path 'library-su19'
    Cloning into '/home/kevin/cs61bl/su19-kevinlin1/library-su19'...
    Submodule path 'library-su19': checked out '83521d6f6b313145e1debdeab8b5f25c3bbf6854'
  3. Ta-da! You now have libraries!

    $ ls library-su19/

If Git is having trouble running the submodule command and cloning the library-su19 repository, try running the following commands to make sure the remote repository URL is correctly defined.

git config --file=.gitmodules submodule.library-su19.url
git submodule sync
git submodule update --init

Below is shown the directory structure of library-su19. Look inside the folder and make sure you see the six .jar files listed below. If you’re using your operating system’s file explorer the jar part might not show up in the filenames, and that’s OK.

   └── javalib
       ├── algs4.jar
       ├── hamcrest-core-1.3.jar
       ├── jh61b.jar
       ├── junit-4.12.jar
       ├── stdlib-package.jar
       └── stdlib.jar

Importing Libraries

Double check on You should see that some of the words in the file are red, specifically Test and assertEquals. If you mouse over them, you’ll see a message along the lines of “cannot resolve symbol”. The trouble is that we haven’t told IntelliJ where to find the CS 61B libraries we just pulled.

  1. Click File -> Project Structure in the top left of IntelliJ. A window should pop up, and you should click Libraries on the left panel of this window. When you’ve done so, it’ll look as shown below:

    Project Structure

  2. Click the green plus in the top left of this window and pick Java from among the given choices. This will pop up a window. Click on the javalib folder (which is in library-su19) and press OK. If you get a message that says something like, “IDEA cannot determine what kind of files the chosen items contain”, then you probably selected the wrong folder. Make sure you’ve selected the javalib folder and not the library-su19 folder.

    Press OK a few times, and you’ll find yourself looking at again. This time, the red text should be gone. If it is not, click File -> Project Structure -> Problems -> Fix -> Add to Dependencies -> OK.

    Try running the code by clicking Run -> Run, as shown below.

    Library Files

  3. This will probably pop up a very small dialog window like the one shown. Basically IntelliJ is saying that it isn’t quite sure what you mean by running the program and is giving you two choices: 0. is to edit the configuration before running the program (which we won’t do). 2. is to run the DogTest class, which is what we want. Note that some IntelliJ installations may come installed with an Android JUnit, which you can tell apart by the small green Android icon in place of the usual red-green left-right JUnit icon. Make sure to choose the correct one based on the icon shown in the screenshot below.

    library files

  4. Click on DogTest and a green bar should appear with the message “All 2 tests passed.” as shown below.

    library files

You’ll notice after running your code that the green play and green bug icons in the upper right are now green; this is because IntelliJ remembered what you meant by “Run” for this project and you can now click this button to run your program. You’ll learn more about this over time as we use more advanced features of IntelliJ.

Optional: Embedded Terminal

IntelliJ has the cool feature that you can have a working terminal in the workspace so you don’t have to constantly switch between having IntelliJ and your terminal, if that becomes necessary for whatever reason.

For Mac users, you should be able to skip this setup section. Windows users will likely have to put in a little leg work. This setup assumes you are a Windows user and you have Git Bash installed.

  1. First, find the preferences/settings tab and select it. (Or use Ctrl+Alt+S.)


  2. Type in “terminal” in the search bar. Once there, type in "C:\Program Files (x86)\Git\bin\sh.exe" --login -i into the Shell Path field. Click OK.


  3. To test if you’ve properly set this up, hover over the little box in the bottom left corner and select terminal; the bottom third of your screen should now be a terminal, the equivalent of having git bash right there.

    Terminal Test

  4. Try typing something in! If you’re able to run basic commands like ls or cd or echo 'Hello world' you’ve done it!

    Terminal Test