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| java.util.ListIterator
| ListIterator | | public interface ListIterator extends Iterator<E>(Code) | | 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:
Element(0) Element(1) Element(2) ... Element(n-1)
cursor positions: ^ ^ ^ ^ ^
Note that the
ListIterator.remove and
ListIterator.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
ListIterator.next or
ListIterator.previous() .
This interface is a member of the
Java Collections Framework.
author:
Josh Bloch
version:
1.35, 05/05/07
See Also: Collection
See Also: List
See Also: Iterator
See Also: Enumeration
See Also: List.listIterator
since:
1.2 |
| Method Summary | |
| void | add(E e)
Inserts the specified element into the list (optional operation).
The element is inserted immediately before the next element that
would be returned by
ListIterator.next , if any, and after the next
element that would be returned by
ListIterator.previous , if any. | | 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
ListIterator.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
ListIterator.previous . | | void | remove()
Removes from the list the last element that was returned by
ListIterator.next or
ListIterator.previous (optional operation). | | void | set(E e)
Replaces the last element returned by
ListIterator.next or
ListIterator.previous with the specified element (optional operation). |
| add | | void add(E e)(Code) | | Inserts the specified element into the list (optional operation).
The element is inserted immediately before the next element that
would be returned by
ListIterator.next , if any, and after the next
element that would be returned by
ListIterator.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 - the element to insert
throws:
UnsupportedOperationException - if the add method isnot supported by this list iterator
throws:
ClassCastException - if the class of the specified elementprevents it from being added to this list
throws:
IllegalArgumentException - if some aspect of this elementprevents it from being added to this list |
| hasNext | | boolean hasNext()(Code) | | Returns
true if this list iterator has more elements when
traversing the list in the forward direction. (In other words,
returns
true if
ListIterator.next would return an element rather
than throwing an exception.)
true if the list iterator has more elements whentraversing the list in the forward direction |
| hasPrevious | | boolean hasPrevious()(Code) | | Returns
true if this list iterator has more elements when
traversing the list in the reverse direction. (In other words,
returns
true if
ListIterator.previous would return an element
rather than throwing an exception.)
true if the list iterator has more elements whentraversing the list in the reverse direction |
| next | | E next()(Code) | | 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
ListIterator.previous to go back and forth.
(Note that alternating calls to
next and
previous will return the same element repeatedly.)
the next element in the list
throws:
NoSuchElementException - if the iteration has no next element |
| nextIndex | | int nextIndex()(Code) | | Returns the index of the element that would be returned by a
subsequent call to
ListIterator.next . (Returns list size if the list
iterator is at the end of the list.)
the index of the element that would be returned by asubsequent call to next , or list size if the listiterator is at the end of the list |
| previous | | E previous()(Code) | | 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
ListIterator.next to go back and forth. (Note that alternating calls
to
next and
previous will return the same
element repeatedly.)
the previous element in the list
throws:
NoSuchElementException - if the iteration has no previouselement |
| previousIndex | | int previousIndex()(Code) | | Returns the index of the element that would be returned by a
subsequent call to
ListIterator.previous . (Returns -1 if the list
iterator is at the beginning of the list.)
the index of the element that would be returned by asubsequent call to previous , or -1 if the listiterator is at the beginning of the list |
| remove | | void remove()(Code) | | Removes from the list the last element that was returned by
ListIterator.next or
ListIterator.previous (optional operation). This call can
only be made once per call to
next or
previous .
It can be made only if
ListIterator.add 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
throws:
IllegalStateException - if neither next nor previous have been called, or remove or add have been called after the last call to next or previous |
| set | | void set(E e)(Code) | | Replaces the last element returned by
ListIterator.next or
ListIterator.previous with the specified element (optional operation).
This call can be made only if neither
ListIterator.remove nor
ListIterator.add have been called after the last call to
next or
previous .
Parameters:
e - the element with which to replace the last element returned by next or previous
throws:
UnsupportedOperationException - if the set operationis not supported by this list iterator
throws:
ClassCastException - if the class of the specified elementprevents it from being added to this list
throws:
IllegalArgumentException - if some aspect of the specifiedelement prevents it from being added to this list
throws:
IllegalStateException - if neither next nor previous have been called, or remove or add have been called after the last call to next or previous |
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