ListIterator
interface ListIterator<E : Any!> : MutableIterator<E>
| java.util.ListIterator |
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: ^ ^ ^ ^ ^
remove and set(java.lang.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.
Summary
| Public methods | |
|---|---|
| abstract Unit |
add(e: E)Inserts the specified element into the list (optional operation). |
| abstract Boolean |
hasNext()Returns |
| abstract Boolean |
Returns |
| abstract E |
next()Returns the next element in the list and advances the cursor position. |
| abstract Int |
Returns the index of the element that would be returned by a subsequent call to |
| abstract E |
previous()Returns the previous element in the list and moves the cursor position backwards. |
| abstract Int |
Returns the index of the element that would be returned by a subsequent call to |
| abstract Unit |
remove()Removes from the list the last element that was returned by |
| abstract Unit |
set(e: E)Replaces the last element returned by |
Public methods
add
abstract fun add(e: E): Unit
Inserts the specified element into the list (optional operation). The element is inserted immediately before the element that would be returned by 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 |
E: the element to insert |
| Exceptions | |
|---|---|
java.lang.UnsupportedOperationException |
if the add method is not supported by this list iterator |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this list |
java.lang.IllegalArgumentException |
if some aspect of this element prevents it from being added to this list |
hasNext
abstract fun hasNext(): Boolean
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.)
| Return | |
|---|---|
Boolean |
true if the list iterator has more elements when traversing the list in the forward direction |
hasPrevious
abstract fun hasPrevious(): Boolean
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.)
| Return | |
|---|---|
Boolean |
true if the list iterator has more elements when traversing the list in the reverse direction |
next
abstract fun next(): E
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 previous to go back and forth. (Note that alternating calls to next and previous will return the same element repeatedly.)
| Return | |
|---|---|
E |
the next element in the list |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if the iteration has no next element |
nextIndex
abstract fun nextIndex(): Int
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.)
| Return | |
|---|---|
Int |
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 |
previous
abstract fun previous(): E
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 next to go back and forth. (Note that alternating calls to next and previous will return the same element repeatedly.)
| Return | |
|---|---|
E |
the previous element in the list |
| Exceptions | |
|---|---|
java.util.NoSuchElementException |
if the iteration has no previous element |
previousIndex
abstract fun previousIndex(): Int
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.)
| Return | |
|---|---|
Int |
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 |
remove
abstract fun remove(): Unit
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 add has not been called after the last call to next or previous.
| Exceptions | |
|---|---|
java.lang.UnsupportedOperationException |
if the remove operation is not supported by this list iterator |
java.lang.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
abstract fun set(e: E): Unit
Replaces the last element returned by next or previous with the specified element (optional operation). This call can be made only if neither remove nor add have been called after the last call to next or previous.
| Parameters | |
|---|---|
e |
E: the element with which to replace the last element returned by next or previous |
| Exceptions | |
|---|---|
java.lang.UnsupportedOperationException |
if the set operation is not supported by this list iterator |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this list |
java.lang.IllegalArgumentException |
if some aspect of the specified element prevents it from being added to this list |
java.lang.IllegalStateException |
if neither next nor previous have been called, or remove or add have been called after the last call to next or previous |