public interface ListIterator<E> extends Iterator<E>
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:
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.
Collection
,
List
,
Iterator
,
Enumeration
,
List.listIterator()
Modifier and Type | Method and Description |
---|---|
void |
add(E e)
Inserts the specified element into the list (optional operation).
|
boolean |
hasNext()
Returns
true if this 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.
|
E |
next()
Returns the next element in the list and advances the cursor position.
|
int |
nextIndex()
Returns the index of the element that would be returned by a subsequent call to
next() .
|
E |
previous()
Returns the previous element in the list and moves the cursor position backwards.
|
int |
previousIndex()
Returns the index of the element that would be returned by a subsequent call to
previous() .
|
void |
remove()
Removes from the list the last element that was returned by
next() or
previous() (optional operation).
|
void |
set(E e)
Replaces the last element returned by
next() or
previous() with the specified element (optional operation).
|
forEachRemaining
boolean hasNext()
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.)
E next()
previous()
to go back and forth. (Note that alternating calls to
next
and
previous
will return the same element repeatedly.)
next
in interface
Iterator<E>
NoSuchElementException
- if the iteration has no next element
boolean hasPrevious()
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.)
true
if the list iterator has more elements when traversing the list in the reverse direction
E previous()
next()
to go back and forth. (Note that alternating calls to
next
and
previous
will return the same element repeatedly.)
NoSuchElementException
- if the iteration has no previous element
int nextIndex()
next()
. (Returns list size if the list iterator is at the end of the list.)
next
, or list size if the list iterator is at the end of the list
int previousIndex()
previous()
. (Returns -1 if the list iterator is at the beginning of the list.)
previous
, or -1 if the list iterator is at the beginning of the list
void remove()
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
.
remove
in interface
Iterator<E>
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)
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
.
e
- the element with which to replace the last element returned by
next
or
previous
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
void add(E e)
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
.)
e
- the element to insert
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