public
interface
ListIterator
implements
Iterator<E>
| java.util.ListIterator<E> |
An iterator for lists that allows the programmer
to traverse the list in either direction, modify
the list during iteration, and obtain the iterator's
current position in the list. A ListIterator
has no current element; its cursor position always
lies between the element that would be returned by a call
to previous() and the element that would be
returned by a call to next().
An iterator for a list of length n has n+1 possible
cursor positions, as illustrated by the carets (^) below:
Developers
Element(0) Element(1) Element(2) ... Element(n-1)
cursor positions: ^ ^ ^ ^ ^
Note that the remove() and set(Object) methods are
not defined in terms of the cursor position; they are defined to
operate on the last element returned by a call to next() or
previous().
This interface is a member of the Java Collections Framework.
Public methods | |
|---|---|
abstract
void
|
add(E e)
Inserts the specified element into the list (optional operation). |
abstract
boolean
|
hasNext()
Returns |
abstract
boolean
|
hasPrevious()
Returns |
abstract
E
|
next()
Returns the next element in the list and advances the cursor position. |
abstract
int
|
nextIndex()
Returns the index of the element that would be returned by a
subsequent call to |
abstract
E
|
previous()
Returns the previous element in the list and moves the cursor position backwards. |
abstract
int
|
previousIndex()
Returns the index of the element that would be returned by a
subsequent call to |
abstract
void
|
remove()
Removes from the list the last element that was returned by |
abstract
void
|
set(E e)
Replaces the last element returned by |
Inherited methods | |
|---|---|
 From
interface
java.util.Iterator
| |
void add (E e)
Inserts the specified element into the list (optional operation).
The element is inserted immediately before the element that
would be returned by next(), if any, and after the element
that would be returned by previous(), if any. (If the
list contains no elements, the new element becomes the sole element
on the list.) The new element is inserted before the implicit
cursor: a subsequent call to next would be unaffected, and a
subsequent call to previous would return the new element.
(This call increases by one the value that would be returned by a
call to nextIndex or previousIndex.)
| Parameters | |
|---|---|
e |
E:
the element to insert |
| Throws | |
|---|---|
UnsupportedOperationException |
if the add method is
not supported by this list iterator |
ClassCastException |
if the class of the specified element prevents it from being added to this list |
IllegalArgumentException |
if some aspect of this element prevents it from being added to this list |
boolean hasNext ()
Returns true if this list iterator has more elements when
traversing the list in the forward direction. (In other words,
returns true if next() would return an element rather
than throwing an exception.)
| Returns | |
|---|---|
boolean |
true if the list iterator has more elements when
traversing the list in the forward direction
|
boolean hasPrevious ()
Returns true if this list iterator has more elements when
traversing the list in the reverse direction. (In other words,
returns true if previous() would return an element
rather than throwing an exception.)
| Returns | |
|---|---|
boolean |
true if the list iterator has more elements when
traversing the list in the reverse direction
|
E next ()
Returns the next element in the list and advances the cursor position.
This method may be called repeatedly to iterate through the list,
or intermixed with calls to previous() to go back and forth.
(Note that alternating calls to next and previous
will return the same element repeatedly.)
| Returns | |
|---|---|
E |
the next element in the list |
| Throws | |
|---|---|
NoSuchElementException |
if the iteration has no next element |
int nextIndex ()
Returns the index of the element that would be returned by a
subsequent call to next(). (Returns list size if the list
iterator is at the end of the list.)
| Returns | |
|---|---|
int |
the index of the element that would be returned by a
subsequent call to next, or list size if the list
iterator is at the end of the list
|
E previous ()
Returns the previous element in the list and moves the cursor
position backwards. This method may be called repeatedly to
iterate through the list backwards, or intermixed with calls to
next() to go back and forth. (Note that alternating calls
to next and previous will return the same
element repeatedly.)
| Returns | |
|---|---|
E |
the previous element in the list |
| Throws | |
|---|---|
NoSuchElementException |
if the iteration has no previous element |
int previousIndex ()
Returns the index of the element that would be returned by a
subsequent call to previous(). (Returns -1 if the list
iterator is at the beginning of the list.)
| Returns | |
|---|---|
int |
the index of the element that would be returned by a
subsequent call to previous, or -1 if the list
iterator is at the beginning of the list
|
void remove ()
Removes from the list the last element that was returned by next() or previous() (optional operation). This call can
only be made once per call to next or previous.
It can be made only if add(E) has not been
called after the last call to next or previous.
| Throws | |
|---|---|
UnsupportedOperationException |
if the remove
operation is not supported by this list iterator |
IllegalStateException |
if neither next nor
previous have been called, or remove or
add have been called after the last call to
next or previous
|
void set (E e)
Replaces the last element returned by next() or
previous() with the specified element (optional operation).
This call can be made only if neither remove() nor add(E) have been called after the last call to next or
previous.
| Parameters | |
|---|---|
e |
E:
the element with which to replace the last element returned by
next or previous |
| Throws | |
|---|---|
UnsupportedOperationException |
if the set operation
is not supported by this list iterator |
ClassCastException |
if the class of the specified element prevents it from being added to this list |
IllegalArgumentException |
if some aspect of the specified element prevents it from being added to this list |
IllegalStateException |
if neither next nor
previous have been called, or remove or
add have been called after the last call to
next or previous
|