Java: Dynamically Load Multiple Versions of Same Class

Based on your answer to my question, it seems you want to define a game interface and then plug in any number of AI implementations, probably configured from a .properties file. This is fairly standard use of an API interface.

You define an EngineInterface providing a method that accepts game state and returns the move. Then you define multiple classes that all implement EngineInterface. Your driver reads a property file to get the names of the implementation classes, instantiates them with Class.forName() and stores them in a list and/or map. Then when the driver gets requests it invokes each implementation in turn and keeps track of the results.

Have you tried something like:

class Move;   // some data type that is able to represent the AI's move.

interface AI {

    Move getMove( GameState state);
};

AIOne implements AI;
AITwo implements AI;

Each class would implement its own algorithm for generating a move, but would be called but called by common method

It is possible to do what you want with OSGI but you could as well use a custom classloader. The idea is that you have to instanciate a classloader for every version of the class you want to load. Here you can find a good explanation.

But I think what you really need to solve your problem is something based on interfaces like described by Jim Garrison or Dave L Delaney...