java.util
Interface Iterator<E>

All Known Subinterfaces:
ListIterator sample code for java.util.ListIterator definition code for java.util.ListIterator <E>
All Known Implementing Classes:
BeanContextSupport.BCSIterator sample code for java.beans.beancontext.BeanContextSupport.BCSIterator definition code for java.beans.beancontext.BeanContextSupport.BCSIterator , Scanner sample code for java.util.Scanner definition code for java.util.Scanner

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:

This interface is a member of the Java Collections Framework.

Since:
1.2
See Also:
Collection sample code for java.util.Collection definition code for java.util.Collection , ListIterator sample code for java.util.ListIterator definition code for java.util.ListIterator , Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration

Method Summary
 boolean hasNext sample code for java.util.Iterator.hasNext() definition code for java.util.Iterator.hasNext() ()
          Returns true if the iteration has more elements.
 E next sample code for java.util.Iterator.next() definition code for java.util.Iterator.next() ()
          Returns the next element in the iteration.
 void remove sample code for java.util.Iterator.remove() definition code for java.util.Iterator.remove() ()
          Removes from the underlying collection the last element returned by the iterator (optional operation).
 

Method Detail

hasNext sample code for java.util.Iterator.hasNext() definition code for java.util.Iterator.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 iterator has more elements.

next sample code for java.util.Iterator.next() definition code for java.util.Iterator.next()

E next()
Returns the next element in the iteration. Calling this method repeatedly until the hasNext() sample code for java.util.Iterator.hasNext() definition code for java.util.Iterator.hasNext() method returns false will return each element in the underlying collection exactly once.

Returns:
the next element in the iteration.
Throws:
NoSuchElementException sample code for java.util.NoSuchElementException definition code for java.util.NoSuchElementException - iteration has no more elements.

remove sample code for java.util.Iterator.remove() definition code for java.util.Iterator.remove()

void remove()
Removes from the underlying collection the last element returned by the 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 sample code for java.lang.UnsupportedOperationException definition code for java.lang.UnsupportedOperationException - if the remove operation is not supported by this Iterator.
IllegalStateException sample code for java.lang.IllegalStateException definition code for java.lang.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.