Package java.util

Interface Iterator<E>

  • Type Parameters:
    E - the type of elements returned by this iterator
    All Known Subinterfaces:
    ListIterator<E>

    public interface Iterator<E>
    An iterator over a collection. Iterator takes the place of Enumeration in the Java Collections Framework. Iterators differ from enumerations in two ways:
    • Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics.
    • Method names have been improved.

    This interface is a member of the Java Collections Framework

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      boolean hasNext()
      Returns true if the iteration has more elements.
      E next()
      Returns the next element in the iteration.
      void remove()
      Removes from the underlying collection the last element returned by this iterator (optional operation).
    • Method Detail

      • hasNext

        boolean hasNext()
        Returns true if the iteration has more elements. (In other words, returns true if next() would return an element rather than throwing an exception.)
        Returns:
        true if the iteration has more elements
      • next

        E next()
        Returns the next element in the iteration.
        Returns:
        the next element in the iteration
        Throws:
        NoSuchElementException - if the iteration has no more elements
      • remove

        void remove()
        Removes from the underlying collection the last element returned by this iterator (optional operation). This method can be called only once per call to next(). The behavior of an iterator is unspecified if the underlying collection is modified while the iteration is in progress in any way other than by calling this method.
        Throws:
        UnsupportedOperationException - if the remove operation is not supported by this iterator
        IllegalStateException - if the next method has not yet been called, or the remove method has already been called after the last call to the next method