java.util

Interface ListIterator<E>

All Superinterfaces:
Iterator<E>

public interface ListIterator<E>
extends Iterator<E>

An extended version of Iterator to support the extra features of Lists. The elements may be accessed in forward or reverse order, elements may be replaced as well as removed, and new elements may be inserted, during the traversal of the list.

A list with n elements provides n+1 iterator positions (the front, the end, or between two elements). Note that remove and set operate on the last element returned, whether it was by next or previous.

Since:
1.2
See Also:
Collection, List, Iterator, Enumeration

Method Summary

void
add(E o)
Insert an element into the list at the current position of the iterator (optional operation).
boolean
hasNext()
Tests whether there are elements remaining in the list in the forward direction.
boolean
hasPrevious()
Tests whether there are elements remaining in the list in the reverse direction.
E
next()
Obtain the next element in the list in the forward direction.
int
nextIndex()
Find the index of the element that would be returned by a call to next.
E
previous()
Obtain the next element in the list in the reverse direction.
int
previousIndex()
Find the index of the element that would be returned by a call to previous.
void
remove()
Remove from the list the element last returned by a call to next or previous (optional operation).
void
set(E o)
Replace the element last returned by a call to next or previous with a given object (optional operation).

Methods inherited from interface java.util.Iterator<E>

hasNext, next, remove

Method Details

add

public void add(E o)
Insert an element into the list at the current position of the iterator (optional operation). The element is inserted in between the element that would be returned by previous and the element that would be returned by next. After the insertion, a subsequent call to next is unaffected, but a call to previous returns the item that was added. The values returned by nextIndex() and previousIndex() are incremented.
Parameters:
o - the object to insert into the list
Throws:
ClassCastException - if the object is of a type which cannot be added to this list.
IllegalArgumentException - if some other aspect of the object stops it being added to this list.
UnsupportedOperationException - if this ListIterator does not support the add operation.

hasNext

public boolean hasNext()
Tests whether there are elements remaining in the list in the forward direction. In other words, next() will not fail with a NoSuchElementException.
Specified by:
hasNext in interface Iterator<E>
Returns:
true if the list continues in the forward direction

hasPrevious

public boolean hasPrevious()
Tests whether there are elements remaining in the list in the reverse direction. In other words, previous() will not fail with a NoSuchElementException.
Returns:
true if the list continues in the reverse direction

next

public E next()
Obtain the next element in the list in the forward direction. Repeated calls to next may be used to iterate over the entire list, or calls to next and previous may be used together to go forwards and backwards. Alternating calls to next and previous will return the same element.
Specified by:
next in interface Iterator<E>
Returns:
the next element in the list in the forward direction
Throws:
NoSuchElementException - if there are no more elements

nextIndex

public int nextIndex()
Find the index of the element that would be returned by a call to next. If hasNext() returns false, this returns the list size.
Returns:
the index of the element that would be returned by next()

previous

public E previous()
Obtain the next element in the list in the reverse direction. Repeated calls to previous may be used to iterate backwards over the entire list, or calls to next and previous may be used together to go forwards and backwards. Alternating calls to next and previous will return the same element.
Returns:
the next element in the list in the reverse direction
Throws:
NoSuchElementException - if there are no more elements

previousIndex

public int previousIndex()
Find the index of the element that would be returned by a call to previous. If hasPrevious() returns false, this returns -1.
Returns:
the index of the element that would be returned by previous()

remove

public void remove()
Remove from the list the element last returned by a call to next or previous (optional operation). This method may only be called if neither add nor remove have been called since the last call to next or previous.
Specified by:
remove in interface Iterator<E>
Throws:
IllegalStateException - if neither next or previous have been called, or if add or remove has been called since the last call to next or previous
UnsupportedOperationException - if this ListIterator does not support the remove operation

set

public void set(E o)
Replace the element last returned by a call to next or previous with a given object (optional operation). This method may only be called if neither add nor remove have been called since the last call to next or previous.
Parameters:
o - the object to replace the element with
Throws:
ClassCastException - the object is of a type which cannot be added to this list
IllegalArgumentException - some other aspect of the object stops it being added to this list
IllegalStateException - if neither next or previous have been called, or if add or remove has been called since the last call to next or previous
UnsupportedOperationException - if this ListIterator does not support the set operation

ListIterator.java -- Extended Iterator for iterating over ordered lists Copyright (C) 1998, 1999, 2001, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.