SINGLECOSTAM

public class Singleton {
    private static final int NUMBER_OF_INSTANCES = 3;
    private final static Collection<Singleton> instances = new ArrayList<Singleton>();
    private final Iterator<Singleton> instancesIterator = getInstacesIterator();

    private Singleton() {};

    synchronized public static Singleton getInstance() {
        tryToAllocateNewInstances();
        return instancesIterator.next();
    }

    private static void tryToAllocateNewInstances() {
        if (instances.size() < NUMBER_OF_INSTANCES)
            instances.add(new Singleton());
    }

}