java.util
public class LinkedList<E> extends AbstractSequentialList<E> implements List<E>, Cloneable, Serializable
All of the stack/queue/deque operations could be easily recast in terms of the standard list operations. They're included here primarily for convenience, though they may run slightly faster than the equivalent List operations.
All of the operations perform as could be expected for a doubly-linked list. Operations that index into the list will traverse the list from the begining or the end, whichever is closer to the specified index.
Note that this implementation is not synchronized. If multiple threads access a list concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no such object exists, the list should be "wrapped" using the Collections.synchronizedList method. This is best done at creation time, to prevent accidental unsynchronized access to the list:
List list = Collections.synchronizedList(new LinkedList(...));
The iterators returned by the this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the Iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.
This class is a member of the Java Collections Framework.
Since: 1.2
Version: 1.53, 06/22/03
See Also: List ArrayList Vector synchronizedList
| Constructor Summary | |
|---|---|
| LinkedList()
Constructs an empty list. | |
| LinkedList(Collection<? extends E> c)
Constructs a list containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
| |
| Method Summary | |
|---|---|
| boolean | add(E o)
Appends the specified element to the end of this list.
|
| void | add(int index, E element)
Inserts the specified element at the specified position in this list.
|
| boolean | addAll(Collection<? extends E> c)
Appends all of the elements in the specified collection to the end of
this list, in the order that they are returned by the specified
collection's iterator. |
| boolean | addAll(int index, Collection<? extends E> c)
Inserts all of the elements in the specified collection into this
list, starting at the specified position. |
| void | addFirst(E o)
Inserts the given element at the beginning of this list.
|
| void | addLast(E o)
Appends the given element to the end of this list. |
| void | clear()
Removes all of the elements from this list. |
| Object | clone()
Returns a shallow copy of this LinkedList. |
| boolean | contains(Object o)
Returns true if this list contains the specified element.
|
| E | get(int index)
Returns the element at the specified position in this list.
|
| E | getFirst()
Returns the first element in this list.
|
| E | getLast()
Returns the last element in this list.
|
| int | indexOf(Object o)
Returns the index in this list of the first occurrence of the
specified element, or -1 if the List does not contain this
element. |
| int | lastIndexOf(Object o)
Returns the index in this list of the last occurrence of the
specified element, or -1 if the list does not contain this
element. |
| ListIterator<E> | listIterator(int index)
Returns a list-iterator of the elements in this list (in proper
sequence), starting at the specified position in the list.
|
| boolean | remove(Object o)
Removes the first occurrence of the specified element in this list. |
| E | remove(int index)
Removes the element at the specified position in this list. |
| E | removeFirst()
Removes and returns the first element from this list.
|
| E | removeLast()
Removes and returns the last element from this list.
|
| E | set(int index, E element)
Replaces the element at the specified position in this list with the
specified element.
|
| int | size()
Returns the number of elements in this list.
|
| Object[] | toArray()
Returns an array containing all of the elements in this list
in the correct order.
|
| <T> T[] | toArray(T[] a)
Returns an array containing all of the elements in this list in
the correct order; the runtime type of the returned array is that of
the specified array. |
Parameters: c the collection whose elements are to be placed into this list.
Throws: NullPointerException if the specified collection is null.
Parameters: o element to be appended to this list.
Returns: true (as per the general contract of Collection.add).
Parameters: index index at which the specified element is to be inserted. element element to be inserted.
Throws: IndexOutOfBoundsException if the specified index is out of range (index < 0 || index > size()).
Parameters: c the elements to be inserted into this list.
Returns: true if this list changed as a result of the call.
Throws: NullPointerException if the specified collection is null.
Parameters: index index at which to insert first element from the specified collection. c elements to be inserted into this list.
Returns: true if this list changed as a result of the call.
Throws: IndexOutOfBoundsException if the specified index is out of range (index < 0 || index > size()). NullPointerException if the specified collection is null.
Parameters: o the element to be inserted at the beginning of this list.
Parameters: o the element to be inserted at the end of this list.
Returns: a shallow copy of this LinkedList instance.
Parameters: o element whose presence in this list is to be tested.
Returns: true if this list contains the specified element.
Parameters: index index of element to return.
Returns: the element at the specified position in this list.
Throws: IndexOutOfBoundsException if the specified index is is out of range (index < 0 || index >= size()).
Returns: the first element in this list.
Throws: NoSuchElementException if this list is empty.
Returns: the last element in this list.
Throws: NoSuchElementException if this list is empty.
Parameters: o element to search for.
Returns: the index in this list of the first occurrence of the specified element, or -1 if the list does not contain this element.
Parameters: o element to search for.
Returns: the index in this list of the last occurrence of the specified element, or -1 if the list does not contain this element.
The list-iterator is fail-fast: if the list is structurally modified at any time after the Iterator is created, in any way except through the list-iterator's own remove or add methods, the list-iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Parameters: index index of first element to be returned from the list-iterator (by a call to next).
Returns: a ListIterator of the elements in this list (in proper sequence), starting at the specified position in the list.
Throws: IndexOutOfBoundsException if index is out of range (index < 0 || index > size()).
See Also: List
Parameters: o element to be removed from this list, if present.
Returns: true if the list contained the specified element.
Parameters: index the index of the element to removed.
Returns: the element previously at the specified position.
Throws: IndexOutOfBoundsException if the specified index is out of range (index < 0 || index >= size()).
Returns: the first element from this list.
Throws: NoSuchElementException if this list is empty.
Returns: the last element from this list.
Throws: NoSuchElementException if this list is empty.
Parameters: index index of element to replace. element element to be stored at the specified position.
Returns: the element previously at the specified position.
Throws: IndexOutOfBoundsException if the specified index is out of range (index < 0 || index >= size()).
Returns: the number of elements in this list.
Returns: an array containing all of the elements in this list in the correct order.
If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the collection is set to null. This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.
Parameters: a the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.
Returns: an array containing the elements of the list.
Throws: ArrayStoreException if the runtime type of a is not a supertype of the runtime type of every element in this list. NullPointerException if the specified array is null.