Iterator<E> class Null safety

An interface for getting items, one at a time, from an object.

The for-in construct transparently uses Iterator to test for the end of the iteration, and to get each item (or element).

If the object iterated over is changed during the iteration, the behavior is unspecified.

The Iterator is initially positioned before the first element. Before accessing the first element the iterator must thus be advanced using moveNext to point to the first element. If no element is left, then moveNext returns false, and all further calls to moveNext will also return false.

The current value must not be accessed before calling moveNext or after a call to moveNext has returned false.

A typical usage of an Iterator looks as follows:

var it = obj.iterator;
while (it.moveNext()) {
  use(it.current);
}

See also: Iteration in the library tour