Atm, it'll take me a bit to get back to you on this: I'm in Italy with very little time. But I have not forgotten you! Sean On May 31, 2016, at 1:22 AM, Atm Golam Bari <[log in to unmask]> wrote: > I am facing difficulty implementing two population based coevolutionary steady state algorithm. This is what I did > >>> MultiPopCoevolutionaryEvaluator (under ec/coevolve/) extends SteadyStateEvaluator and overrides evaluatePopulation(, , ) >>> GroupedProblem inside MultiPopCoevolutionaryEvlauator is changed into SimpleProblem >>> Inside performCoevolutionaryEvaluation (, , ), writing prob.evluate(....) is called two times each for one population to be workable with SimpleProblem. > > But when I want to catch (say, print out the genotype of incoming individual or playing with other individuals in different population) the individuals in evaluate (inside problem class), it shows me NullPointerException. But same individual can be printed ,just before sending to the problem class, inside evaluator. > > What am I missing? Is it a right way to handle SSEA in a two pop coevoluton? Any suggestion or new approach is highly appreciated.