Setting up DrJava for GridWorld

The AP CS A exam isn’t requiring GridWorld (the old required lab) after the 2014 exam, but teachers are still allowed to use it. However, I recommend checking out Greenfoot instead at Greenfoot is a free IDE that makes it easy to create 2D animations and games in Java.

If you want to use GridWorld you can still get the GridWorld materials at To allow DrJava to run any GridWord code you need to tell it where to find the gridworld.jar file. To do this you add the gridworld.jar file to the classpath, which is a list of the places to look for classes. GridWorld isn’t part of the Java language, but is a set of additional classes developed for the Advanced Placement Computer Science A exam so we need to tell the compiler where to find these classes.

To add to the classpath in DrJava click on Edit in the top menu and then Preferences and finally on Resource Locations. Then click on the Add button below the Extra Classpath area. Use the file browser to find the gridworld.jar file and select that file. Then click on OK.


Figure 3: Adding gridworld.jar to the classpath in DrJava