java.util.AbstractCollection<E>
java.util.AbstractList<E>
java.util.AbstractSequentialList<E>
java.util.LinkedList<E>
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JavaTM 2 Platform Standard Ed. 5.0 |
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java.lang.Object
E - the type of elements held in this collectionpublic class LinkedList<E>
Linked list implementation of the List interface. Implements all optional list operations, and permits all elements (including null). In addition to implementing the List interface, the LinkedList class provides uniformly named methods to get, remove and insert an element at the beginning and end of the list. These operations allow linked lists to be used as a stack, queue, or double-ended queue (deque).
The class implements the Queue interface, providing first-in-first-out queue operations for add, poll, etc. Other stack and 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 beginning 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.
List,
ArrayList,
Vector,
Collections.synchronizedList(List),
Serialized Form| Field Summary |
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| Fields inherited from class java.util.AbstractList |
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modCount |
| Constructor Summary | |
|---|---|
LinkedList()
Constructs an empty list. |
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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. |
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| Method Summary | ||
|---|---|---|
boolean |
add(E o)
Appends the specified element to the end of this list. |
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void |
add(int index,
E element)
Inserts the specified element at the specified position in this list. |
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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. |
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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. |
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void |
addFirst(E o)
Inserts the given element at the beginning of this list. |
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void |
addLast(E o)
Appends the given element to the end of this list. |
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void |
clear()
Removes all of the elements from this list. |
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Object |
clone()
Returns a shallow copy of this LinkedList. |
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boolean |
contains(Object o)
Returns true if this list contains the specified element. |
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E |
element()
Retrieves, but does not remove, the head (first element) of this list. |
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E |
get(int index)
Returns the element at the specified position in this list. |
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E |
getFirst()
Returns the first element in this list. |
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E |
getLast()
Returns the last element in this list. |
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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. |
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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. |
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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. |
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boolean |
offer(E o)
Adds the specified element as the tail (last element) of this list. |
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E |
peek()
Retrieves, but does not remove, the head (first element) of this list. |
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E |
poll()
Retrieves and removes the head (first element) of this list. |
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E |
remove()
Retrieves and removes the head (first element) of this list. |
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E |
remove(int index)
Removes the element at the specified position in this list. |
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boolean |
remove(Object o)
Removes the first occurrence of the specified element in this list. |
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E |
removeFirst()
Removes and returns the first element from this list. |
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E |
removeLast()
Removes and returns the last element from this list. |
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E |
set(int index,
E element)
Replaces the element at the specified position in this list with the specified element. |
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int |
size()
Returns the number of elements in this list. |
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Object[] |
toArray()
Returns an array containing all of the elements in this list in the correct order. |
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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. |
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| Methods inherited from class java.util.AbstractSequentialList |
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iterator |
| Methods inherited from class java.util.AbstractList |
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equals, hashCode, listIterator, removeRange, subList |
| Methods inherited from class java.util.AbstractCollection |
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containsAll, isEmpty, removeAll, retainAll, toString |
| Methods inherited from class java.lang.Object |
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finalize, getClass, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface java.util.List |
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containsAll, equals, hashCode, isEmpty, iterator, listIterator, removeAll, retainAll, subList |
| Constructor Detail |
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public LinkedList()
public LinkedList(Collection<? extends E> c)
c - the collection whose elements are to be placed into this list.
NullPointerException - if the specified collection is null.| Method Detail |
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public E getFirst()
NoSuchElementException - if this list is empty.public E getLast()
NoSuchElementException - if this list is empty.public E removeFirst()
NoSuchElementException - if this list is empty.public E removeLast()
NoSuchElementException - if this list is empty.public void addFirst(E o)
o - the element to be inserted at the beginning of this list.public void addLast(E o)
o - the element to be inserted at the end of this list.public boolean contains(Object o)
contains in interface Collection<E>contains in interface List<E>contains in class AbstractCollection<E>o - element whose presence in this list is to be tested.
public int size()
size in interface Collection<E>size in interface List<E>size in class AbstractCollection<E>public boolean add(E o)
add in interface Collection<E>add in interface List<E>add in class AbstractList<E>o - element to be appended to this list.
public boolean remove(Object o)
remove in interface Collection<E>remove in interface List<E>remove in class AbstractCollection<E>o - element to be removed from this list, if present.
public boolean addAll(Collection<? extends E> c)
addAll in interface Collection<E>addAll in interface List<E>addAll in class AbstractCollection<E>c - the elements to be inserted into this list.
NullPointerException - if the specified collection is null.AbstractCollection.add(Object)
public boolean addAll(int index,
Collection<? extends E> c)
addAll in interface List<E>addAll in class AbstractSequentialList<E>index - index at which to insert first element
from the specified collection.c - elements to be inserted into this list.
IndexOutOfBoundsException - if the specified index is out of
range (index < 0 || index > size()).
NullPointerException - if the specified collection is null.public void clear()
clear in interface Collection<E>clear in interface List<E>clear in class AbstractList<E>public E get(int index)
get in interface List<E>get in class AbstractSequentialList<E>index - index of element to return.
IndexOutOfBoundsException - if the specified index is out of
range (index < 0 || index >= size()).
public E set(int index,
E element)
set in interface List<E>set in class AbstractSequentialList<E>index - index of element to replace.element - element to be stored at the specified position.
IndexOutOfBoundsException - if the specified index is out of
range (index < 0 || index >= size()).
public void add(int index,
E element)
add in interface List<E>add in class AbstractSequentialList<E>index - index at which the specified element is to be inserted.element - element to be inserted.
IndexOutOfBoundsException - if the specified index is out of
range (index < 0 || index > size()).public E remove(int index)
remove in interface List<E>remove in class AbstractSequentialList<E>index - the index of the element to removed.
IndexOutOfBoundsException - if the specified index is out of
range (index < 0 || index >= size()).public int indexOf(Object o)
indexOf in interface List<E>indexOf in class AbstractList<E>o - element to search for.
public int lastIndexOf(Object o)
lastIndexOf in interface List<E>lastIndexOf in class AbstractList<E>o - element to search for.
public E peek()
peek in interface Queue<E>public E element()
element in interface Queue<E>NoSuchElementException - if this queue is empty.public E poll()
poll in interface Queue<E>public E remove()
remove in interface Queue<E>NoSuchElementException - if this queue is empty.public boolean offer(E o)
offer in interface Queue<E>o - the element to add.
public ListIterator<E> listIterator(int index)
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.
listIterator in interface List<E>listIterator in class AbstractSequentialList<E>index - index of first element to be returned from the
list-iterator (by a call to next).
IndexOutOfBoundsException - if index is out of range
(index < 0 || index > size()).List.listIterator(int)public Object clone()
clone in class ObjectCloneablepublic Object[] toArray()
toArray in interface Collection<E>toArray in interface List<E>toArray in class AbstractCollection<E>Arrays.asList(Object[])public <T> T[] toArray(T[] a)
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.
toArray in interface Collection<E>toArray in interface List<E>toArray in class AbstractCollection<E>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.
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.
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JavaTM 2 Platform Standard Ed. 5.0 |
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Copyright 2004 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.