Package java.util

Interface Iterator<E>

Type Parameters:
E - the type of object returned by the iterator.
All Known Subinterfaces:
HeaderElementIterator, HeaderIterator, ListIterator<E>, TokenIterator
All Known Implementing Classes:
BasicHeaderElementIterator, BasicHeaderIterator, BasicListHeaderIterator, BasicTokenIterator, Scanner
public interface Iterator<E>
An iterator over a sequence of objects, such as a collection.

If a collection has been changed since the iterator was created, methods next and hasNext() may throw a ConcurrentModificationException. It is not possible to guarantee that this mechanism works in all cases of unsynchronized concurrent modification. It should only be used for debugging purposes. Iterators with this behavior are called fail-fast iterators.

Implementing Iterable and returning an Iterator allows your class to be used as a collection with the enhanced for loop.

  • Method Summary

    Modifier and Type Method Description
    boolean hasNext()
    Returns true if there is at least one more element, false otherwise.
    E next()
    Returns the next object and advances the iterator.
    void remove()
    Removes the last object returned by next from the collection.

  • Method Details

    • hasNext

      boolean hasNext()
      Returns true if there is at least one more element, false otherwise.
      See Also:
      next()

    • next

      E next()
      Returns the next object and advances the iterator.
      Returns:
      the next object.
      Throws:
      NoSuchElementException - if there are no more elements.
      See Also:
      hasNext()

    • remove

      void remove()
      Removes the last object returned by next from the collection. This method can only be called once between each call to next.
      Throws:
      UnsupportedOperationException - if removing is not supported by the collection being iterated.
      IllegalStateException - if next has not been called, or remove has already been called after the last call to next.