ConcurrentModificationException? [duplicate]

Answer 1

workingList.remove(compareTo);

You are modifying a collection while iterating on it.

You should use something like:

ListIterator<Time[]> it = workingList.listIterator();

while (it.hasNext()) {
  Time[] time = it.next();
  ..
  it.remove();
}

There are ways also without using the list iterator but this seems the more correct.

Answer 2

My suggestion is that you use Collections.sort() for ordering lists. It does the sorting for you, and makes it a lot more readable what you are trying to do. You'll need to specify your own Comparator when calling the method - as such:

    Collections.sort(workingList,new Comparator<Time[]>() {
        @Override
        public int compare(Time[] time1, Time[] time2) {
            return time1[0].before(time2[0]);
        }
    });

This will sort workingList as your specs.