Two Way IterleavingIterator

Infographic

I wanted to solve iterating across multiple iterators with a round-robin fashion.

Features

• Iterating with next()
• Iterating with prev()
• Check prev with hasPrev()
• Check next with hasNext()

Usage

List<Integer> foo = new ArrayList<>();
foo.add(1);

List<Integer> bar = new ArrayList<>();
bar.add(2);

List<Integer> baz = new ArrayList<>();
baz.add(3);
baz.add(4);
baz.add(5);

List<Iterator<Integer>> myIters = new ArrayList<>();
myIters.add(foo.listIterator());
myIters.add(bar.listIterator());
myIters.add(baz.listIterator());

InterleavingIterator<Integer> ill = new InterleavingIterator(myIters);
while(ill.hasNext()) {
    System.out.println(ill.next());
}
while(ill.hasPrev()) {
    System.out.println(ill.prev());
}

would produce

1
2
3
4
5
5
4
3
2
1