Apache Commons Collections 4.4 · org.apache.commons.collections4.iterators.ReverseListIterator

Iterates backwards through a List, starting with the last element and continuing to the first. This is useful for looping around a list in reverse order without needing to actually reverse the list.

The first call to next() will return the last element from the list, and so on. The hasNext() method works in concert with the next() method as expected. However, the nextIndex() method returns the correct index in the list, thus it starts high and reduces as the iteration continues. The previous methods work similarly.

Modifier and Type	Field and Description
private ListIterator<E>	iterator The list iterator being wrapped.
private final List<E>	list The list being wrapped.
private boolean	validForUpdate Flag to indicate if updating is possible at the moment.

Constructor Summary

Access	Constructor and Description
public	ReverseListIterator(final List<E> the list to create a reversed iterator for list) Constructor that wraps a list.

Method Summary

Modifier and Type	Method and Description
public void	add(final E the object to add obj) Implements java.util.ListIterator.add. Adds a new element to the list between the next and previous elements.
public boolean	Returns: true if there is another element hasNext() Implements java.util.ListIterator.hasNext, java.util.Iterator.hasNext. Checks whether there is another element.
public boolean	Returns: true if there is a previous element hasPrevious() Implements java.util.ListIterator.hasPrevious, org.apache.commons.collections4.OrderedIterator.hasPrevious. Checks whether there is a previous element.
public E	Returns: the next element in the iterator next() Implements java.util.ListIterator.next, java.util.Iterator.next. Gets the next element.
public int	Returns: the index of the next element in the iterator nextIndex() Implements java.util.ListIterator.nextIndex. Gets the index of the next element.
public E	Returns: the previous element in the iterator previous() Implements java.util.ListIterator.previous, org.apache.commons.collections4.OrderedIterator.previous. Gets the previous element.
public int	Returns: the index of the previous element in the iterator previousIndex() Implements java.util.ListIterator.previousIndex. Gets the index of the previous element.
public void	remove() Overrides default java.util.Iterator.remove. Implements java.util.ListIterator.remove. Removes the last returned element.
public void	reset() Implements org.apache.commons.collections4.ResettableIterator.reset. Resets the iterator back to the start (which is the end of the list as this is a reversed iterator)
public void	set(final E the object to set obj) Implements java.util.ListIterator.set. Replaces the last returned element.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

iterator	back to summary
private ListIterator<E> iterator The list iterator being wrapped.

list	back to summary
private final List<E> list The list being wrapped.

validForUpdate	back to summary
private boolean validForUpdate Flag to indicate if updating is possible at the moment.

Constructor Detail

ReverseListIterator	back to summary
public ReverseListIterator(final List<E> list) Constructor that wraps a list. Parameters list:List<E> the list to create a reversed iterator for Exceptions NullPointerException: if the list is null

ReverseListIterator

back to summary

public ReverseListIterator(final List<E> list)

Constructor that wraps a list.

Parameters

list:List<E>: the list to create a reversed iterator for

Exceptions

NullPointerException:: if the list is null

Method Detail

add	back to summary
public void add(final E obj) Implements java.util.ListIterator.add. Adds a new element to the list between the next and previous elements. Parameters obj:E the object to add Annotations @Override Exceptions UnsupportedOperationException: if the list is unmodifiable IllegalStateException: if the iterator is not in a valid state for set

add

back to summary

public void add(final E obj)

Implements java.util.ListIterator.add.

Adds a new element to the list between the next and previous elements.

Parameters

obj:E: the object to add

Annotations

@Override

Exceptions

UnsupportedOperationException:: if the list is unmodifiable
IllegalStateException:: if the iterator is not in a valid state for set

hasNext	back to summary
public boolean hasNext() Implements java.util.ListIterator.hasNext, java.util.Iterator.hasNext. Checks whether there is another element. Returns:boolean true if there is another element Annotations @Override

hasNext

back to summary

public boolean hasNext()

Implements java.util.ListIterator.hasNext, java.util.Iterator.hasNext.

Checks whether there is another element.

Returns:boolean

true if there is another element

Annotations

@Override

hasPrevious	back to summary
public boolean hasPrevious() Implements java.util.ListIterator.hasPrevious, org.apache.commons.collections4.OrderedIterator.hasPrevious. Checks whether there is a previous element. Returns:boolean true if there is a previous element Annotations @Override

hasPrevious

back to summary

public boolean hasPrevious()

Implements java.util.ListIterator.hasPrevious, org.apache.commons.collections4.OrderedIterator.hasPrevious.

Checks whether there is a previous element.

Returns:boolean

true if there is a previous element

Annotations

@Override

next	back to summary
public E next() Implements java.util.ListIterator.next, java.util.Iterator.next. Gets the next element. The next element is the previous in the list. Returns:E the next element in the iterator Annotations @Override

back to summary

public E next()

Implements java.util.ListIterator.next, java.util.Iterator.next.

Gets the next element. The next element is the previous in the list.

Returns:E

the next element in the iterator

Annotations

@Override

nextIndex	back to summary
public int nextIndex() Implements java.util.ListIterator.nextIndex. Gets the index of the next element. Returns:int the index of the next element in the iterator Annotations @Override

nextIndex

back to summary

public int nextIndex()

Implements java.util.ListIterator.nextIndex.

Gets the index of the next element.

Returns:int

the index of the next element in the iterator

Annotations

@Override

previous	back to summary
public E previous() Implements java.util.ListIterator.previous, org.apache.commons.collections4.OrderedIterator.previous. Gets the previous element. The next element is the previous in the list. Returns:E the previous element in the iterator Annotations @Override

back to summary

public E previous()

Implements java.util.ListIterator.previous, org.apache.commons.collections4.OrderedIterator.previous.

Gets the previous element. The next element is the previous in the list.

Returns:E

the previous element in the iterator

Annotations

@Override

previousIndex	back to summary
public int previousIndex() Implements java.util.ListIterator.previousIndex. Gets the index of the previous element. Returns:int the index of the previous element in the iterator Annotations @Override

previousIndex

back to summary

public int previousIndex()

Implements java.util.ListIterator.previousIndex.

Gets the index of the previous element.

Returns:int

the index of the previous element in the iterator

Annotations

@Override

remove	back to summary
public void remove() Overrides default java.util.Iterator.remove. Implements java.util.ListIterator.remove. Removes the last returned element. Annotations @Override Exceptions UnsupportedOperationException: if the list is unmodifiable IllegalStateException: if there is no element to remove

remove

back to summary

public void remove()

Overrides default java.util.Iterator.remove.

Implements java.util.ListIterator.remove.

Removes the last returned element.

Annotations

@Override

Exceptions

UnsupportedOperationException:: if the list is unmodifiable
IllegalStateException:: if there is no element to remove

reset	back to summary
public void reset() Implements org.apache.commons.collections4.ResettableIterator.reset. Resets the iterator back to the start (which is the end of the list as this is a reversed iterator) Annotations @Override

reset

back to summary

public void reset()

Implements org.apache.commons.collections4.ResettableIterator.reset.

Resets the iterator back to the start (which is the end of the list as this is a reversed iterator)

Annotations

@Override

set	back to summary
public void set(final E obj) Implements java.util.ListIterator.set. Replaces the last returned element. Parameters obj:E the object to set Annotations @Override Exceptions UnsupportedOperationException: if the list is unmodifiable IllegalStateException: if the iterator is not in a valid state for set

set

back to summary

public void set(final E obj)

Implements java.util.ListIterator.set.

Replaces the last returned element.

Parameters