JavaTM 2 Platform Std. Ed. v1.6.0
java.util
Interface ListIterator<E>
- All Superinterfaces:
- Iterator<E>
public interface ListIterator<E> - extends Iterator<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:
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.
- Since:
- 1.2
- See Also:
Collection ,
List ,
Iterator ,
Enumeration ,
List.listIterator()
Method Summary |
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. |
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. |
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). |
hasNext
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.)
- Specified by:
hasNext in interface Iterator<E>
- Returns:
- true if the list iterator has more elements when
traversing the list in the forward direction.
next
E next()
- Returns the next element in the list. 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.)
- Specified by:
next in interface Iterator<E>
- Returns:
- the next element in the list.
- Throws:
NoSuchElementException - if the iteration has no next element.
hasPrevious
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:
- true if the list iterator has more elements when
traversing the list in the reverse direction.
previous
E previous()
- Returns the previous element in the list. 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:
- the previous element in the list.
- Throws:
NoSuchElementException - if the iteration has no previous
element.
nextIndex
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:
- the index of the element that would be returned by a subsequent
call to next, or list size if list iterator is at end
of list.
previousIndex
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:
- the index of the element that would be returned by a subsequent
call to previous, or -1 if list iterator is at
beginning of list.
remove
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 ListIterator.add has not been called after
the last call to next or previous.
- Specified by:
remove in interface Iterator<E>
- Throws:
UnsupportedOperationException - if the remove
operation is not supported by this list iterator.
IllegalStateException - 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)
- Replaces the last element returned by next or
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 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.
add
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 next, if any, and after the next 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 - 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.
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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