compact1, compact2, compact3
java.util
Interface ListIterator<E>
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- 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. AListIteratorhas no current element; its cursor position always lies between the element that would be returned by a call toprevious()and the element that would be returned by a call tonext(). An iterator for a list of lengthnhasn+1possible cursor positions, as illustrated by the carets (^) below:Element(0) Element(1) Element(2) ... Element(n-1) cursor positions: ^ ^ ^ ^ ^
Note that theremove()andset(Object)methods are not defined in terms of the cursor position; they are defined to operate on the last element returned by a call tonext()orprevious().This interface is a member of the Java Collections Framework.
- Since:
- 1.2
- See Also:
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Collection,List,Iterator,Enumeration,List.listIterator()
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method and Description voidadd(E e)Inserts the specified element into the list (optional operation).booleanhasNext()Returnstrueif this list iterator has more elements when traversing the list in the forward direction.booleanhasPrevious()Returnstrueif this list iterator has more elements when traversing the list in the reverse direction.Enext()Returns the next element in the list and advances the cursor position.intnextIndex()Returns the index of the element that would be returned by a subsequent call tonext().Eprevious()Returns the previous element in the list and moves the cursor position backwards.intpreviousIndex()Returns the index of the element that would be returned by a subsequent call toprevious().voidremove()Removes from the list the last element that was returned bynext()orprevious()(optional operation).voidset(E e)Replaces the last element returned bynext()orprevious()with the specified element (optional operation).-
Methods inherited from interface java.util.Iterator
forEachRemaining
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Method Detail
hasNext
boolean hasNext()
Returnstrueif this list iterator has more elements when traversing the list in the forward direction. (In other words, returnstrueifnext()would return an element rather than throwing an exception.)
next
E next()
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 toprevious()to go back and forth. (Note that alternating calls tonextandpreviouswill return the same element repeatedly.)- Specified by:
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nextin interfaceIterator<E> - Returns:
- the next element in the list
- Throws:
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NoSuchElementException- if the iteration has no next element
hasPrevious
boolean hasPrevious()
Returnstrueif this list iterator has more elements when traversing the list in the reverse direction. (In other words, returnstrueifprevious()would return an element rather than throwing an exception.)- Returns:
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trueif the list iterator has more elements when traversing the list in the reverse direction
previous
E 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 tonext()to go back and forth. (Note that alternating calls tonextandpreviouswill return the same element repeatedly.)- Returns:
- the previous element in the list
- Throws:
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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 tonext(). (Returns list size if the list iterator is at the end of the list.)- Returns:
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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 toprevious(). (Returns -1 if the list iterator is at the beginning of the list.)- Returns:
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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
void remove()
Removes from the list the last element that was returned bynext()orprevious()(optional operation). This call can only be made once per call tonextorprevious. It can be made only ifadd(E)has not been called after the last call tonextorprevious.- Specified by:
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removein interfaceIterator<E> - Throws:
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UnsupportedOperationException- if theremoveoperation is not supported by this list iterator -
IllegalStateException- if neithernextnorprevioushave been called, orremoveoraddhave been called after the last call tonextorprevious
set
void set(E e)
Replaces the last element returned bynext()orprevious()with the specified element (optional operation). This call can be made only if neitherremove()noradd(E)have been called after the last call tonextorprevious.- Parameters:
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e- the element with which to replace the last element returned bynextorprevious - Throws:
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UnsupportedOperationException- if thesetoperation 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 neithernextnorprevioushave been called, orremoveoraddhave been called after the last call tonextorprevious
add
void add(E e)
Inserts the specified element into the list (optional operation). The element is inserted immediately before the element that would be returned bynext(), if any, and after the element that would be returned byprevious(), 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 tonextwould be unaffected, and a subsequent call topreviouswould return the new element. (This call increases by one the value that would be returned by a call tonextIndexorpreviousIndex.)- Parameters:
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e- the element to insert - Throws:
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UnsupportedOperationException- if theaddmethod 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
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Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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