Question

I want to use Guava to implement a “peekable” ListIterator that lets me peek at the previous and next list elements without moving the cursor. This is akin to Guava’s PeekingIterator, only bidirectional because Guava’s PeekingIterator only has a next() method, not a previous().

Does this need to be implemented by writing a new PeekingListIterator class or is there an Guava-intended way to combine the two concepts?

Answer 1

Where’s the value in introducing a new “peeking” concept to an iterator that’s already easily scrollable in both directions?

If you really want it, you could just implement two trivial static helpers:

public static <T> T peekNext(ListIterator<T> iterator) {
  T next = iterator.next();
  iterator.previous();
  return next;
}

public static <T> T peekPrevious(ListIterator<T> iterator) {
  T previous = iterator.previous();
  iterator.next();
  return previous;
}