Round Robin Iterators

Problem

Given an array of iterators, how would you implement a new iterator that cycles through them in a round robin pattern? hasNext should return true if any input iterator hasNext. Next should follow the following example. Suppose the array has iterators backed by queues (0 1 2) (3 4 5 6) (7 8) (write on the whiteboard). Know that you can’t index into these. They only implement hasNext and next. I want an iterator where next() goes [0,3,7,1,4,8,2,5,6]. Make sense?

Use cases

• Load balancing.
• Distributing work.