I am using ECJ for Genetic Programming.
Once I have evolved an individual, I would like to test its
performance on an independent set of test cases to see how it
generalizes. How do I do this?

The best individual is printed out in KozaStatistics.finalStatistics
It can be accessed as

However, I want to evaluate this individial on a seperate set of test cases.
I could write a seperate method (e.g. generalization) in my problem
class, but how would I call it?
The generalization method will be identical  to the evalute method in
my problem class, but on a seperate set of data.

Any ideas?

I am sure someone must have done this before if they have coded GP

John Woodward.