import java.util.List;
import java.util.ArrayList;
import java.rmi.Remote;

/**
 * Group of instances of a service.
 * @author Ken Baclawski
 */
@Copyright
public class ServiceGroup {
    /**
     * Set of remote objects.
     */
    private List<Remote> objects = new ArrayList<Remote>();

    /**
     * Construct a service group.
     */
    public ServiceGroup() {
    }

    /**
     * Add a remote object to the service group.
     * @param obj The remote object being added to the group.
     */
    public void add(Remote obj) {
        objects.add(obj);
    }

    /**
     * Get the next object from the group. If the group has more than one
     * element, then one of them is chosen at random.
     * @return An object from the group or null if there is no object in the
     * group.
     */
    public Remote getNext() {
        int size = objects.size();
        if (size == 0) {
            return null;
        } else if (size == 1) {
            return objects.get(0);
        } else {
            int i = (int)(size * Math.random());
            return objects.get(i);
        }
    }
}