Class JavaMethods GitHub -> Chomp project directory -> CharMatrix class. The CharMatrix code can be copy-and-pasted into Repl.it or DrJava. Make sure you test your code as you go, so you know what the problems are. There is a tester file in the Chomp project directory that works with DrJava.
Using DrJava: how do you run the tests? Answer: Make sure the file CharMatrixTester.java is in your project. Click Compile Project and then Test Project.
CharMatrixTester.java was updated on GitHub; sorry about the incorrect test results.