org.apache.commons.collections.iterators
Class SingletonListIterator

java.lang.Object
  |
  +--org.apache.commons.collections.iterators.SingletonListIterator

All Implemented Interfaces:

Iterator, ListIterator

public class SingletonListIterator

extends Object

implements ListIterator

SingletonIterator is an ListIterator over a single object instance.

Since:

2.1

Version:

$Id: SingletonListIterator.java,v 1.2 2002/08/19 21:56:18 pjack Exp $

Author:

Stephen Colebourne

Constructor Summary

SingletonListIterator(Object object)
Constructs a new SingletonListIterator.

Method Summary

void	add(Object obj) Add always throws UnsupportedOperationException.
boolean	hasNext() Is another object available from the iterator.
boolean	hasPrevious() Is a previous object available from the iterator.
Object	next() Get the next object from the iterator.
int	nextIndex() Returns the index of the element that would be returned by a subsequent call to next.
Object	previous() Get the previous object from the iterator.
int	previousIndex() Returns the index of the element that would be returned by a subsequent call to previous.
void	remove() Remove always throws UnsupportedOperationException.
void	set(Object obj) Set sets the value of the singleton.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SingletonListIterator

public SingletonListIterator(Object object)

Constructs a new SingletonListIterator.

Parameters:

object - the single object to return from the iterator

Method Detail

add

public void add(Object obj)

Add always throws UnsupportedOperationException.

Specified by:

add in interface ListIterator

Throws:

UnsupportedOperationException - always

hasNext

public boolean hasNext()

Is another object available from the iterator.

This returns true if the single object hasn't been returned yet.

Specified by:

hasNext in interface ListIterator

Returns:

true if the single object hasn't been returned yet

hasPrevious

public boolean hasPrevious()

Is a previous object available from the iterator.

This returns true if the single object has been returned.

Specified by:

hasPrevious in interface ListIterator

Returns:

true if the single object has been returned

next

public Object next()

Get the next object from the iterator.

This returns the single object if it hasn't been returned yet.

Specified by:

next in interface ListIterator

Returns:

the single object

Throws:

NoSuchElementException - if the single object has already been returned

nextIndex

public int nextIndex()

Returns the index of the element that would be returned by a subsequent call to next.

Specified by:

nextIndex in interface ListIterator

Returns:

0 or 1 depending on current state.

previous

public Object previous()

Get the previous object from the iterator.

This returns the single object if it has been returned.

Specified by:

previous in interface ListIterator

Returns:

the single object

Throws:

NoSuchElementException - if the single object has not already been returned

previousIndex

public int previousIndex()

Returns the index of the element that would be returned by a subsequent call to previous. A return value of -1 indicates that the iterator is currently at the start.

Specified by:

previousIndex in interface ListIterator

Returns:

0 or -1 depending on current state.

remove

public void remove()

Remove always throws UnsupportedOperationException.

Specified by:

remove in interface ListIterator

Throws:

UnsupportedOperationException - always

set

public void set(Object obj)

Set sets the value of the singleton.

Specified by:

set in interface ListIterator

Parameters:

obj - the object to set

Throws:

IllegalStateException - if next has not been called