| java.util.ListIterator
| ListIterator | | public interface ListIterator extends Iterator(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(). In a list of
length n, there are n+1 valid
index values, from 0 to n, inclusive.
Element(0) Element(1) Element(2) ... Element(n)
^ ^ ^ ^ ^
Index: 0 1 2 3 n+1
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:
1.16, 02/02/00
See Also: Collection
See Also: List
See Also: Iterator
See Also: Enumeration
since:
1.2 |
| Method Summary | |
| void | add(Object o)
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. | | Object | 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. | | Object | 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(Object o)
Replaces the last element returned by next or
previous with the specified element (optional operation). |
| add | | void add(Object o)(Code) | | 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:
o - the element to insert.
exception:
UnsupportedOperationException - if the add method isnot supported by this list iterator.
exception:
ClassCastException - if the class of the specified elementprevents it from being added to this list.
exception:
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 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 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 | | Object next()(Code) | | 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.)
the next element in the list.
exception:
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 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 a subsequentcall to next, or list size if list iterator is at endof list. |
| previous | | Object previous()(Code) | | 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.)
the previous element in the list.
exception:
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 previous. (Returns -1 if the list iterator is at the
beginning of the list.)
the index of the element that would be returned by a subsequentcall to previous, or -1 if list iterator is atbeginning of list. |
| remove | | void remove()(Code) | | 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.
exception:
UnsupportedOperationException - if the removeoperation is not supported by this list iterator.
exception:
IllegalStateException - neither next norprevious have been called, or remove oradd have been called after the last call to *next or previous. |
| set | | void set(Object o)(Code) | | 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:
o - the element with which to replace the last element returned bynext or previous.
exception:
UnsupportedOperationException - if the set operationis not supported by this list iterator.
exception:
ClassCastException - if the class of the specified elementprevents it from being added to this list.
exception:
IllegalArgumentException - if some aspect of the specifiedelement prevents it from being added to this list.
exception:
IllegalStateException - if neither next norprevious have been called, or remove oradd have been called after the last call tonext or previous. |
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