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Posted on Mon 15 September 2008 in Projects

GWJeroo is a library that lets students run Jeroo programs in GridWorld. GWJeroo is intended for students in Pre-AP and AP classes who are transitioning from Jeroo to Java.

I developed this in 2007 when I was a high school computer science teacher. I no longer teach, so I don't expect to update it.


  • GWJeroo code looks almost identical to Jeroo code.
  • GWJeroo can use any feature in the Java language including variables, for loops, and out.println().
  • GWJeroo is just a standard Java library that is distributed in a jar file. It compiles and runs in any normal Java IDE.
  • When a GWJeroo program runs, students run their program one line at a time using Gridworld's step button.
  • GWJeroo can read .jev files from Jeroo.
  • In GWJeroo, the class Jeroo extends the class Actor. This means you can call any of Actor's methods, such as setColor() or moveTo() (But I don't plan on telling my students this too quickly. (Things like moveTo() make some problems too easy!))
  • The island can have any number of Jeroos. You can also have multiple classes that extend Jeroo, so you can have different types of Jeroos.


Here's some assignments and resources other people created for GWJeroo: and .

I made a few small changes to the original GridWorld source code. They are documented in the file gridworld.diff .

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Jeff McGee — builder, problem solver, teacher, and general nerd.

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