ListIterator (Java Platform SE 6)

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java.util
interface ListIterator

All Superinterfaces:: Iterator

Most common way to construct:

ArrayList aList = …;

ListIterator listIterator = aList.listIterator();

Based on 18 examples

public interface ListIterator
extends Iterator

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 {@link #remove} and {@link #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 {@link #next} or {@link #previous()}.

This interface is a member of the Java Collections Framework.

Method Summary
`void`	`add(Object 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.
`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 e)` Replaces the last element returned by `next` or `previous` with the specified element (optional operation).

Methods inherited from class java.util.Iterator
`hasNext, next, remove`

Method Detail

add

public void add(Object 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.

hasNext

public 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.)

Returns:: true if the list iterator has more elements when traversing the list in the forward direction.

hasPrevious

public 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.

public Object 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.)

Returns:: the next element in the list.

nextIndex

public 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.

public Object 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.

previousIndex

public 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

public 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.

set

public void set(Object 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.