Dear all, In my application, I have extended Evolve class (here called MyEvolve.java). In this class, I need to instantiate an object from another class created by my (let's say MyClass obj = new MyClass()). However, I need to use this object in the evaluate method (implemented in my problem). How could I pass this object from MyEvolve (extending Evolve.java) to MyProblem (public class myProblem extends Problem implements SimpleProblemForm)? This object can not be static, that's why I need to pass as a parameter. However, ECJ will call the evaluate implemented according to SimpleProblemForm (exactly the same parameters). Then, I need to know where ECJ calls evaluate(), then I can change it to call a different evaluate (with an additional param), and add a new evaluate method in SimpleProblemForm (one more parameter: MyClass obj) or implement a new interface (that also implements SimpleProblemForm). Could someone give me directions to solve this, please? Best, Márcio -------- Prof. Dr. Márcio Porto Basgalupp Instituto de Ciência e Tecnologia (ICT) Universidade Federal de São Paulo (UNIFESP) Tel: +55 12 3924-9500 (r: 9762)