I try to find a way to do it but i didn't find out, please let me know if my question has already been asked.
Basically i have a generic interface Evaluator<E, T> with a single method E evaluate(T a, T b) which will be implemented by lot of classes (for each Evaluator implementation correspond a specific algorithm). The class which use those evaluators use an XML configuration file which indicate which Evaluator class to use. To get an Evaluator from a given class name i decided to set a EvaluatorProvider class which build a evaluator from a given classe name.
This method is also generic :
public static <E, T> Evaluator<E, T> newInstance(String className)
I want to ensure that the class found for this name is a valid subclass of Evaluator using isAssignableFrom() :
Evaluator<E, T> evaluatorInstance = null;
try {
Class<?> evaluatorClass = Class.forName(className);
if (!Evaluator.class.isAssignableFrom(evaluatorClass)) {
}
evaluatorInstance = (Evaluator<E, T>) evaluatorClass.newInstance();
}
// Catch clause, etc ...
But it gives me a warning about unchecked cast, i was wondering then how to take in account the generic type provided for the class checking (using isAssignableFrom() or any other valid java mecanism).
Hope it was clear :).
PS : If you have other suggestion for the solution design please let me know, i am curious about the best way to modelize such system in Java, without run in ServiceProvider pattern which is too big for the project need.