Package org.apache.commons.collections4.iterators

Class SingletonListIterator<E>

java.lang.Object

org.apache.commons.collections4.iterators.SingletonListIterator<E>

All Implemented Interfaces:

java.util.Iterator<E>, java.util.ListIterator<E>, OrderedIterator<E>, ResettableIterator<E>, ResettableListIterator<E>

public class SingletonListIterator<E>
extends java.lang.Object
implements ResettableListIterator<E>

SingletonIterator is an ListIterator over a single object instance.

Since:

2.1

Constructor Summary

Constructors

Constructor	Description
SingletonListIterator(E object)	Constructs a new SingletonListIterator.

Method Summary

Modifier and Type	Method	Description
void	add(E obj)	Add always throws UnsupportedOperationException.
boolean	hasNext()	Is another object available from the iterator?
boolean	hasPrevious()	Is a previous object available from the iterator?
E	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.
E	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 the object from this iterator.
void	reset()	Reset the iterator back to the start.
void	set(E obj)	Set sets the value of the singleton.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Constructor Detail

SingletonListIterator

public SingletonListIterator(E object)

Constructs a new SingletonListIterator.

Parameters:

object - the single object to return from the iterator

Method Detail

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 java.util.Iterator<E>

Specified by:

hasNext in interface java.util.ListIterator<E>

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 java.util.ListIterator<E>

Specified by:

hasPrevious in interface OrderedIterator<E>

Returns:

true if the single object has 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 java.util.ListIterator<E>

Returns:

0 or 1 depending on current state.

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 java.util.ListIterator<E>

Returns:

0 or -1 depending on current state.

next

public E 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 java.util.Iterator<E>

Specified by:

next in interface java.util.ListIterator<E>

Returns:

the single object

Throws:

java.util.NoSuchElementException - if the single object has already been returned

previous

public E previous()

Get the previous object from the iterator.

This returns the single object if it has been returned.

Specified by:

previous in interface java.util.ListIterator<E>

Specified by:

previous in interface OrderedIterator<E>

Returns:

the single object

Throws:

java.util.NoSuchElementException - if the single object has not already been returned

remove

public void remove()

Remove the object from this iterator.

Specified by:

remove in interface java.util.Iterator<E>

Specified by:

remove in interface java.util.ListIterator<E>

Throws:

java.lang.IllegalStateException - if the next or previous method has not yet been called, or the remove method has already been called after the last call to next or previous.

add

public void add(E obj)

Add always throws UnsupportedOperationException.

Specified by:

add in interface java.util.ListIterator<E>

Parameters:

obj - the object to add

Throws:

java.lang.UnsupportedOperationException - always

set

public void set(E obj)

Set sets the value of the singleton.

Specified by:

set in interface java.util.ListIterator<E>

Parameters:

obj - the object to set

Throws:

java.lang.IllegalStateException - if next has not been called or the object has been removed

reset

public void reset()

Reset the iterator back to the start.

Specified by:

reset in interface ResettableIterator<E>