math.list

Interface DListIterator

All Superinterfaces:

DForEachIterator, DIterator

public interface DListIterator
extends DForEachIterator

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 DListIterator 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 DForEachIterator.remove() and set(double) methods are not defined in terms of the cursor position; they are defined to operate on the last element returned by a call to DIterator.next() or previous().

Method Summary

Modifier and Type	Method and Description
void	add(double e) Inserts the specified element into the list.
boolean	hasPrevious() Returns true if this list iterator has more elements when traversing the list in the reverse direction.
int	nextIndex() Returns the index of the element that would be returned by a subsequent call to DIterator.next().
double	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	set(double e) Replaces the last element returned by DIterator.next() or previous() with the specified element.

Methods inherited from interface math.fun.DForEachIterator

forEachRemaining, remove

Methods inherited from interface math.fun.DIterator

hasNext, next

Method Detail

hasPrevious

boolean hasPrevious()

Returns true if this list iterator has more elements when traversing the list in the reverse direction.

Returns:

true if the list iterator has more elements when traversing the list in the reverse direction

previous

double 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 DIterator.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 DIterator.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 the list iterator is at the end of the 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 the list iterator is at the beginning of the list

set

void set(double e)

Replaces the last element returned by DIterator.next() or previous() with the specified element. This call can be made only if neither DForEachIterator.remove() nor add(double) 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:

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(double e)

Inserts the specified element into the list. The element is inserted immediately before the element that would be returned by DIterator.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 - the element to insert