On Jan 4, 2016, at 1:50 PM, Axel Kowald <[log in to unmask]> wrote: > But playing with the code I think I spotted a bug in the Sequence class. > The Sequence contructor for Collection does not set "size". Thus if I > create my ParallelSequence with a Collection, size is zero, leading to a > division by zero exception. Looks like a bug to me. Try this: public Sequence(Collection collection) { steps = (Steppable[])(collection.toArray( new Steppable[collection.size()])); size = steps.length; } I'll commit that. Sean