Question

Is it possible to merge iterators in Java? I have two iterators and I want to combine/merge them so that I could iterate though their elements in one go (in same loop) rather than two steps. Is that possible?

Note that the number of elements in the two lists can be different therefore one loop over both lists is not the solution.

Iterator<User> pUsers = userService.getPrimaryUsersInGroup(group.getId());
Iterator<User> sUsers = userService.getSecondaryUsersInGroup(group.getId());

while(pUsers.hasNext()) {
  User user = pUsers.next();
  .....
}

while(sUsers.hasNext()) {
  User user = sUsers.next();
  .....
}

Answer 1

Guava (formerly Google Collections) has Iterators.concat.