Summary: Inherited Fields | Ctors | Methods | Inherited Methods | [Expand All]

public class

LinkedList

extends AbstractSequentialList<E>
implements Serializable Cloneable Deque<E> List<E> Queue<E>

java.lang.Object
↳	java.util.AbstractCollection<E>
	↳	java.util.AbstractList<E>
		↳	java.util.AbstractSequentialList<E>
			↳	java.util.LinkedList<E>

Class Overview

LinkedList is an implementation of List, backed by a doubly-linked list. All optional operations including adding, removing, and replacing elements are supported.

All elements are permitted, including null.

This class is primarily useful if you need queue-like behavior. It may also be useful as a list if you expect your lists to contain zero or one element, but still require the ability to scale to slightly larger numbers of elements. In general, though, you should probably use ArrayList if you don't need the queue-like behavior.

Summary

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Inherited Fields

From class java.util.AbstractList

Public Constructors
	LinkedList() Constructs a new empty instance of `LinkedList`.
	LinkedList(Collection<? extends E> collection) Constructs a new instance of `LinkedList` that holds all of the elements contained in the specified `collection`.

Public Methods
boolean	add(E object) Adds the specified object at the end of this `LinkedList`.
void	add(int location, E object) Inserts the specified object into this `LinkedList` at the specified location.
boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified Collection to this `LinkedList`.
boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified collection at the specified location in this `LinkedList`.
void	addFirst(E object) Adds the specified object at the beginning of this `LinkedList`.
void	addLast(E object) Adds the specified object at the end of this `LinkedList`.
void	clear() Removes all elements from this `LinkedList`, leaving it empty.
Object	clone() Returns a new `LinkedList` with the same elements and size as this `LinkedList`.
boolean	contains(Object object) Searches this `LinkedList` for the specified object.
Iterator<E>	descendingIterator() Returns the iterator in reverse order, from tail to head.
E	element() Gets but does not remove the element at the head of the queue.
E	get(int location) Returns the element at the specified location in this list.
E	getFirst() Returns the first element in this `LinkedList`.
E	getLast() Returns the last element in this `LinkedList`.
int	indexOf(Object object) Searches this list for the specified object and returns the index of the first occurrence.
int	lastIndexOf(Object object) Searches this `LinkedList` for the specified object and returns the index of the last occurrence.
ListIterator<E>	listIterator(int location) Returns a ListIterator on the elements of this `LinkedList`.
boolean	offer(E o) Inserts the specified element into the queue provided that the condition allows such an operation.
boolean	offerFirst(E e) Inserts an element at the head of this deque unless it would violate size limit.
boolean	offerLast(E e) Inserts an element at the tail of this deque unless it would violate size limit.
E	peek() Gets but does not remove the element at the head of the queue.
E	peekFirst() Gets but not removes the head element of this deque.
E	peekLast() Gets but not removes the tail element of this deque.
E	poll() Gets and removes the element at the head of the queue, or returns `null` if there is no element in the queue.
E	pollFirst() Gets and removes the head element of this deque.
E	pollLast() Gets and removes the tail element of this deque.
E	pop() Pops the head element of the deque, just same as removeFirst().
void	push(E e) Pushes the element to the deque(at the head of the deque), just same as addFirst(E).
E	remove() Gets and removes the element at the head of the queue.
E	remove(int location) Removes the object at the specified location from this `LinkedList`.
boolean	remove(Object object) Removes one instance of the specified object from this `Collection` if one is contained (optional).
E	removeFirst() Removes the first object from this `LinkedList`.
boolean	removeFirstOccurrence(Object o) Removes the first equivalent element of the specified object.
E	removeLast() Removes the last object from this `LinkedList`.
boolean	removeLastOccurrence(Object o) Removes the last equivalent element of the specified object.
E	set(int location, E object) Replaces the element at the specified location in this `LinkedList` with the specified object.
int	size() Returns the number of elements in this `LinkedList`.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this `LinkedList`.
Object[]	toArray() Returns a new array containing all elements contained in this `LinkedList`.

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Inherited Methods

From class java.util.AbstractSequentialList

From class java.util.AbstractList

boolean	add(E object) Adds the specified object at the end of this List.
void	add(int location, E object) Inserts the specified object into this List at the specified location.
boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified Collection at the specified location in this List.
void	clear() Removes all elements from this list, leaving it empty.
boolean	equals(Object object) Compares the specified object to this list and return true if they are equal.
abstract E	get(int location) Returns the element at the specified location in this list.
int	hashCode() Returns the hash code of this list.
int	indexOf(Object object) Searches this list for the specified object and returns the index of the first occurrence.
Iterator<E>	iterator() Returns an iterator on the elements of this list.
int	lastIndexOf(Object object) Searches this list for the specified object and returns the index of the last occurrence.
ListIterator<E>	listIterator(int location) Returns a list iterator on the elements of this list.
ListIterator<E>	listIterator() Returns a ListIterator on the elements of this list.
E	remove(int location) Removes the object at the specified location from this list.
void	removeRange(int start, int end) Removes the objects in the specified range from the start to the end index minus one.
E	set(int location, E object) Replaces the element at the specified location in this list with the specified object.
List<E>	subList(int start, int end) Returns a part of consecutive elements of this list as a view.

From class java.util.AbstractCollection

boolean	add(E object) Attempts to add `object` to the contents of this `Collection` (optional).
boolean	addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in `collection` to the contents of this `Collection` (optional).
void	clear() Removes all elements from this `Collection`, leaving it empty (optional).
boolean	contains(Object object) Tests whether this `Collection` contains the specified object.
boolean	containsAll(Collection<?> collection) Tests whether this `Collection` contains all objects contained in the specified `Collection`.
boolean	isEmpty() Returns if this `Collection` contains no elements.
abstract Iterator<E>	iterator() Returns an instance of `Iterator` that may be used to access the objects contained by this `Collection`.
boolean	remove(Object object) Removes one instance of the specified object from this `Collection` if one is contained (optional).
boolean	removeAll(Collection<?> collection) Removes all occurrences in this `Collection` of each object in the specified `Collection` (optional).
boolean	retainAll(Collection<?> collection) Removes all objects from this `Collection` that are not also found in the `Collection` passed (optional).
abstract int	size() Returns a count of how many objects this `Collection` contains.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this `Collection`.
Object[]	toArray() Returns a new array containing all elements contained in this `Collection`.
String	toString() Returns the string representation of this `Collection`.

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Called before the object's memory is reclaimed by the VM.
final Class<? extends Object>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

From interface java.lang.Iterable

From interface java.util.Collection

abstract boolean	add(E object) Attempts to add `object` to the contents of this `Collection` (optional).
abstract boolean	addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in `Collection` to the contents of this `Collection` (optional).
abstract void	clear() Removes all elements from this `Collection`, leaving it empty (optional).
abstract boolean	contains(Object object) Tests whether this `Collection` contains the specified object.
abstract boolean	containsAll(Collection<?> collection) Tests whether this `Collection` contains all objects contained in the specified `Collection`.
abstract boolean	equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
abstract int	hashCode() Returns an integer hash code for the receiver.
abstract boolean	isEmpty() Returns if this `Collection` contains no elements.
abstract Iterator<E>	iterator() Returns an instance of `Iterator` that may be used to access the objects contained by this `Collection`.
abstract boolean	remove(Object object) Removes one instance of the specified object from this `Collection` if one is contained (optional).
abstract boolean	removeAll(Collection<?> collection) Removes all occurrences in this `Collection` of each object in the specified `Collection` (optional).
abstract boolean	retainAll(Collection<?> collection) Removes all objects from this `Collection` that are not also found in the `Collection` passed (optional).
abstract int	size() Returns a count of how many objects this `Collection` contains.
abstract <T> T[]	toArray(T[] array) Returns an array containing all elements contained in this `Collection`.
abstract Object[]	toArray() Returns a new array containing all elements contained in this `Collection`.

From interface java.util.Deque

abstract void	addFirst(E e) Inserts an element at the head of this deque if it dose not violate size limit immediately.
abstract void	addLast(E e) Inserts an element at the tail of this deque if it dose not violate size limit immediately.
abstract Iterator<E>	descendingIterator() Returns the iterator in reverse order, from tail to head.
abstract E	getFirst() Gets but not removes the head element of this deque.
abstract E	getLast() Gets but not removes the tail element of this deque.
abstract boolean	offerFirst(E e) Inserts an element at the head of this deque unless it would violate size limit.
abstract boolean	offerLast(E e) Inserts an element at the tail of this deque unless it would violate size limit.
abstract E	peekFirst() Gets but not removes the head element of this deque.
abstract E	peekLast() Gets but not removes the tail element of this deque.
abstract E	pollFirst() Gets and removes the head element of this deque.
abstract E	pollLast() Gets and removes the tail element of this deque.
abstract E	pop() Pops the head element of the deque, just same as removeFirst().
abstract void	push(E e) Pushes the element to the deque(at the head of the deque), just same as addFirst(E).
abstract E	removeFirst() Gets and removes the head element of this deque.
abstract boolean	removeFirstOccurrence(Object o) Removes the first equivalent element of the specified object.
abstract E	removeLast() Gets and removes the tail element of this deque.
abstract boolean	removeLastOccurrence(Object o) Removes the last equivalent element of the specified object.

From interface java.util.List

abstract boolean	add(E object) Adds the specified object at the end of this `List`.
abstract void	add(int location, E object) Inserts the specified object into this `List` at the specified location.
abstract boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified collection to the end of this `List`.
abstract boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified collection at the specified location in this `List`.
abstract void	clear() Removes all elements from this `List`, leaving it empty.
abstract boolean	contains(Object object) Tests whether this `List` contains the specified object.
abstract boolean	containsAll(Collection<?> collection) Tests whether this `List` contains all objects contained in the specified collection.
abstract boolean	equals(Object object) Compares the given object with the `List`, and returns true if they represent the same object using a class specific comparison.
abstract E	get(int location) Returns the element at the specified location in this `List`.
abstract int	hashCode() Returns the hash code for this `List`.
abstract int	indexOf(Object object) Searches this `List` for the specified object and returns the index of the first occurrence.
abstract boolean	isEmpty() Returns whether this `List` contains no elements.
abstract Iterator<E>	iterator() Returns an iterator on the elements of this `List`.
abstract int	lastIndexOf(Object object) Searches this `List` for the specified object and returns the index of the last occurrence.
abstract ListIterator<E>	listIterator(int location) Returns a list iterator on the elements of this `List`.
abstract ListIterator<E>	listIterator() Returns a `List` iterator on the elements of this `List`.
abstract E	remove(int location) Removes the object at the specified location from this `List`.
abstract boolean	remove(Object object) Removes the first occurrence of the specified object from this `List`.
abstract boolean	removeAll(Collection<?> collection) Removes all occurrences in this `List` of each object in the specified collection.
abstract boolean	retainAll(Collection<?> collection) Removes all objects from this `List` that are not contained in the specified collection.
abstract E	set(int location, E object) Replaces the element at the specified location in this `List` with the specified object.
abstract int	size() Returns the number of elements in this `List`.
abstract List<E>	subList(int start, int end) Returns a `List` of the specified portion of this `List` from the given start index to the end index minus one.
abstract <T> T[]	toArray(T[] array) Returns an array containing all elements contained in this `List`.
abstract Object[]	toArray() Returns an array containing all elements contained in this `List`.

From interface java.util.Queue

Public Constructors

public LinkedList ()

Since: API Level 1

Constructs a new empty instance of LinkedList.

public LinkedList (Collection<? extends E> collection)

Since: API Level 1

Constructs a new instance of LinkedList that holds all of the elements contained in the specified collection. The order of the elements in this new LinkedList will be determined by the iteration order of collection.

Parameters

collection	the collection of elements to add.

Public Methods

public boolean add (E object)

Since: API Level 1

Adds the specified object at the end of this LinkedList.

Parameters

object	the object to add.

Returns

always true

public void add (int location, E object)

Since: API Level 1

Inserts the specified object into this LinkedList at the specified location. The object is inserted before any previous element at the specified location. If the location is equal to the size of this LinkedList, the object is added at the end.

Parameters

location	the index at which to insert.
object	the object to add.

Throws

IndexOutOfBoundsException	if `location < 0 \|\| >= size()`

public boolean addAll (Collection<? extends E> collection)

Since: API Level 1

Adds the objects in the specified Collection to this LinkedList.

Parameters

collection	the collection of objects.

Returns

true if this LinkedList is modified, false otherwise.

public boolean addAll (int location, Collection<? extends E> collection)

Since: API Level 1

Inserts the objects in the specified collection at the specified location in this LinkedList. The objects are added in the order they are returned from the collection's iterator.

Parameters

location	the index at which to insert.
collection	the collection of objects

Returns

true if this LinkedList is modified, false otherwise.

Throws

ClassCastException	if the class of an object is inappropriate for this list.
IllegalArgumentException	if an object cannot be added to this list.
IndexOutOfBoundsException	if `location < 0 \|\| > size()`

public void addFirst (E object)

Since: API Level 1

Adds the specified object at the beginning of this LinkedList.

Parameters

object	the object to add.

public void addLast (E object)

Since: API Level 1

Adds the specified object at the end of this LinkedList.

Parameters

object	the object to add.

public void clear ()

Since: API Level 1

Removes all elements from this LinkedList, leaving it empty.

public Object clone ()

Since: API Level 1

Returns a new LinkedList with the same elements and size as this LinkedList.

Returns

a shallow copy of this LinkedList.

public boolean contains (Object object)

Since: API Level 1

Searches this LinkedList for the specified object.

Parameters

object	the object to search for.

Returns

true if object is an element of this LinkedList, false otherwise

public Iterator<E> descendingIterator ()

Since: API Level 9

Returns the iterator in reverse order, from tail to head.

Returns

the iterator in reverse order

public E element ()

Since: API Level 1

Gets but does not remove the element at the head of the queue. Throws a NoSuchElementException if there is no element in the queue.

Returns

the element at the head of the queue.

public E get (int location)

Since: API Level 1

Returns the element at the specified location in this list.

Parameters

location	the index of the element to return.

Returns

the element at the specified index.

public E getFirst ()

Since: API Level 1

Returns the first element in this LinkedList.

Returns

the first element.

Throws

NoSuchElementException	if this `LinkedList` is empty.

public E getLast ()

Since: API Level 1

Returns the last element in this LinkedList.

Returns

the last element

Throws

NoSuchElementException	if this `LinkedList` is empty

public int indexOf (Object object)

Since: API Level 1

Searches this list for the specified object and returns the index of the first occurrence.

Parameters

object	the object to search for.

Returns

the index of the first occurrence of the object, or -1 if it was not found.

public int lastIndexOf (Object object)

Since: API Level 1

Searches this LinkedList for the specified object and returns the index of the last occurrence.

Parameters

object	the object to search for

Returns

the index of the last occurrence of the object, or -1 if it was not found.

public ListIterator<E> listIterator (int location)

Since: API Level 1

Returns a ListIterator on the elements of this LinkedList. The elements are iterated in the same order that they occur in the LinkedList. The iteration starts at the specified location.

Parameters

location	the index at which to start the iteration

Returns

a ListIterator on the elements of this LinkedList

Throws

IndexOutOfBoundsException	if `location < 0 \|\| >= size()`

public boolean offer (E o)

Since: API Level 1

Inserts the specified element into the queue provided that the condition allows such an operation. The method is generally preferable to add(E), since the latter might throw an exception if the operation fails.

Parameters

o	the specified element to insert into the queue.

Returns

true if the operation succeeds and false if it fails.

public boolean offerFirst (E e)

Since: API Level 9

Inserts an element at the head of this deque unless it would violate size limit. It is better than the addFirst(E) method in a size-limited deque, because the latter one may fail to add the element only by throwing an exception.

Parameters

e	the element

Returns

true if the operation succeeds or false if it fails.

public boolean offerLast (E e)

Since: API Level 9

Inserts an element at the tail of this deque unless it would violate size limit. It is better than the addLast(E) method in a size-limited deque, because the latter one may fail to add the element only by throwing an exception.

Parameters

e	the element

Returns

true if the operation succeeds or false if it fails

public E peek ()

Since: API Level 1

Gets but does not remove the element at the head of the queue.

Returns

the element at the head of the queue or null if there is no element in the queue.

public E peekFirst ()

Since: API Level 9

Gets but not removes the head element of this deque. This method returns null if the deque is empty.

Returns

the head element or null if the deque is empty

public E peekLast ()

Since: API Level 9

Gets but not removes the tail element of this deque. This method returns null if the deque is empty.

Returns

the tail element or null if the deque is empty

public E poll ()

Since: API Level 1

Gets and removes the element at the head of the queue, or returns null if there is no element in the queue.

Returns

the element at the head of the queue or null if there is no element in the queue.

public E pollFirst ()

Since: API Level 9

Gets and removes the head element of this deque. This method returns null if the deque is empty.

Returns

the head element or null if the deque is empty

public E pollLast ()

Since: API Level 9

Gets and removes the tail element of this deque. This method returns null if the deque is empty.

Returns

the tail element or null if the deque is empty

public E pop ()

Since: API Level 9

Pops the head element of the deque, just same as removeFirst().

Returns

the head element

public void push (E e)

Since: API Level 9

Pushes the element to the deque(at the head of the deque), just same as addFirst(E).

Parameters

e	the element

public E remove ()

Since: API Level 1

Gets and removes the element at the head of the queue. Throws a NoSuchElementException if there is no element in the queue.

Returns

the element at the head of the queue.

public E remove (int location)

Since: API Level 1

Removes the object at the specified location from this LinkedList.

Parameters

location	the index of the object to remove

Returns

the removed object

Throws

IndexOutOfBoundsException	if `location < 0 \|\| >= size()`

public boolean remove (Object object)

Since: API Level 1

Removes one instance of the specified object from this Collection if one is contained (optional). This implementation iterates over this Collection and tests for each element e returned by the iterator, whether e is equal to the given object. If object != null then this test is performed using object.equals(e), otherwise using object == null. If an element equal to the given object is found, then the remove method is called on the iterator and true is returned, false otherwise. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

Parameters

object	the object to remove.

Returns

true if this Collection is modified, false otherwise.

public E removeFirst ()

Since: API Level 1

Removes the first object from this LinkedList.

Returns

the removed object.

Throws

NoSuchElementException	if this `LinkedList` is empty.

public boolean removeFirstOccurrence (Object o)

Since: API Level 9

Removes the first equivalent element of the specified object. If the deque does not contain the element, it is unchanged and returns false.

Parameters

o	the element to be removed

Returns

true if the operation succeeds or false if the deque does not contain the element.

public E removeLast ()

Since: API Level 1

Removes the last object from this LinkedList.

Returns

the removed object.

Throws

NoSuchElementException	if this `LinkedList` is empty.

public boolean removeLastOccurrence (Object o)

Since: API Level 9

Removes the last equivalent element of the specified object. If the deque does not contain the element, it is unchanged and returns false.

Parameters

o	the element to be removed

Returns

true if the operation succeeds or false if the deque does not contain the element.

public E set (int location, E object)

Since: API Level 1

Replaces the element at the specified location in this LinkedList with the specified object.

Parameters

location	the index at which to put the specified object.
object	the object to add.

Returns

the previous element at the index.

Throws

ClassCastException	if the class of an object is inappropriate for this list.
IllegalArgumentException	if an object cannot be added to this list.
IndexOutOfBoundsException	if `location < 0 \|\| >= size()`

public int size ()

Since: API Level 1

Returns the number of elements in this LinkedList.

Returns

the number of elements in this LinkedList.

public T[] toArray (T[] contents)

Since: API Level 1

Returns an array containing all elements contained in this LinkedList. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this LinkedList, the array element following the collection elements is set to null.

Parameters

contents	the array.

Returns

an array of the elements from this LinkedList.

Throws

ArrayStoreException	if the type of an element in this `LinkedList` cannot be stored in the type of the specified array.

public Object[] toArray ()

Since: API Level 1

Returns a new array containing all elements contained in this LinkedList.

Returns

an array of the elements from this LinkedList.

Interfaces

Classes

Enums

Exceptions

Errors

LinkedList

Class Overview

Summary

Public Constructors

public LinkedList ()

public LinkedList (Collection<? extends E> collection)

Parameters

Public Methods

public boolean add (E object)

Parameters

Returns

public void add (int location, E object)

Parameters

Throws

public boolean addAll (Collection<? extends E> collection)

Parameters

Returns

public boolean addAll (int location, Collection<? extends E> collection)

Parameters

Returns

Throws

public void addFirst (E object)

Parameters

public void addLast (E object)

Parameters

public void clear ()

See Also

public Object clone ()

Returns

See Also

public boolean contains (Object object)

Parameters

Returns

public Iterator<E> descendingIterator ()

Returns

See Also

public E element ()

Returns

public E get (int location)

Parameters

Returns

public E getFirst ()

Returns

Throws

public E getLast ()

Returns

Throws

public int indexOf (Object object)

Parameters

Returns

public int lastIndexOf (Object object)

Parameters

Returns

public ListIterator<E> listIterator (int location)

Parameters

Returns

Throws

See Also

public boolean offer (E o)

Parameters

Returns

public boolean offerFirst (E e)

Parameters

Returns

See Also

public boolean offerLast (E e)

Parameters

Returns

See Also

public E peek ()

Returns

public E peekFirst ()

Returns

See Also

public E peekLast ()