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

public class

LinkedList

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

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

Class Overview

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.

The class implements the Deque interface, providing first-in-first-out queue operations for add, poll, along with other stack and deque 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 linked 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 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.

Summary

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Inherited Fields

From class java.util.AbstractList

Public Constructors
	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.

Public Methods
boolean	add(E e) 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 e) Inserts the specified element at the beginning of this list.
void	addLast(E e) Appends the specified 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.
Iterator<E>	descendingIterator() Returns an iterator over the elements in this deque in reverse sequential order.
E	element() Retrieves, but does not remove, the head (first element) of this list.
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 of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
int	lastIndexOf(Object o) Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the 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	offer(E e) Adds the specified element as the tail (last element) of this list.
boolean	offerFirst(E e) Inserts the specified element at the front of this list.
boolean	offerLast(E e) Inserts the specified element at the end of this list.
E	peek() Retrieves, but does not remove, the head (first element) of this list.
E	peekFirst() Retrieves, but does not remove, the first element of this list, or returns `null` if this list is empty.
E	peekLast() Retrieves, but does not remove, the last element of this list, or returns `null` if this list is empty.
E	poll() Retrieves and removes the head (first element) of this list
E	pollFirst() Retrieves and removes the first element of this list, or returns `null` if this list is empty.
E	pollLast() Retrieves and removes the last element of this list, or returns `null` if this list is empty.
E	pop() Pops an element from the stack represented by this list.
void	push(E e) Pushes an element onto the stack represented by this list.
E	remove() Retrieves and removes the head (first element) of this list.
E	remove(int index) Removes the element at the specified position in this list.
boolean	remove(Object o) Removes the first occurrence of the specified element from this list, if it is present.
E	removeFirst() Removes and returns the first element from this list.
boolean	removeFirstOccurrence(Object o) Removes the first occurrence of the specified element in this list (when traversing the list from head to tail).
E	removeLast() Removes and returns the last element from this list.
boolean	removeLastOccurrence(Object o) Removes the last occurrence of the specified element in this list (when traversing the list from head to tail).
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.
<T> T[]	toArray(T[] a) Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.
Object[]	toArray() Returns an array containing all of the elements in this list in proper sequence (from first to last element).

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Inherited Methods

From class java.util.AbstractSequentialList

From class java.util.AbstractList

boolean	add(E e) Appends the specified element to the end of this list (optional operation).
void	add(int index, E element) Inserts the specified element at the specified position in this list (optional operation). This implementation always throws an `UnsupportedOperationException`.
boolean	addAll(int index, Collection<? extends E> c) Inserts all of the elements in the specified collection into this list at the specified position (optional operation). This implementation gets an iterator over the specified collection and iterates over it, inserting the elements obtained from the iterator into this list at the appropriate position, one at a time, using `add(int, E)`.
void	clear() Removes all of the elements from this list (optional operation).
boolean	equals(Object o) Compares the specified object with this list for equality.
abstract E	get(int index) Returns the element at the specified position in this list.
int	hashCode() Returns the hash code value for this list.
int	indexOf(Object o) Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. This implementation first gets a list iterator (with `listIterator()`).
Iterator<E>	iterator() Returns an iterator over the elements in this list in proper sequence.
int	lastIndexOf(Object o) Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. This implementation first gets a list iterator that points to the end of the list (with `listIterator(size())`).
ListIterator<E>	listIterator(int index) Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. This implementation returns a straightforward implementation of the `ListIterator` interface that extends the implementation of the `Iterator` interface returned by the `iterator()` method.
ListIterator<E>	listIterator() Returns a list iterator over the elements in this list (in proper sequence). This implementation returns `listIterator(0)`.
E	remove(int index) Removes the element at the specified position in this list (optional operation). This implementation always throws an `UnsupportedOperationException`.
void	removeRange(int fromIndex, int toIndex) Removes from this list all of the elements whose index is between `fromIndex`, inclusive, and `toIndex`, exclusive.
E	set(int index, E element) Replaces the element at the specified position in this list with the specified element (optional operation). This implementation always throws an `UnsupportedOperationException`.
List<E>	subList(int fromIndex, int toIndex) Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive. This implementation returns a list that subclasses `AbstractList`.

From class java.util.AbstractCollection

boolean	add(E e) Ensures that this collection contains the specified element (optional operation). This implementation always throws an `UnsupportedOperationException`.
boolean	addAll(Collection<? extends E> c) Adds all of the elements in the specified collection to this collection (optional operation). This implementation iterates over the specified collection, and adds each object returned by the iterator to this collection, in turn.
void	clear() Removes all of the elements from this collection (optional operation). This implementation iterates over this collection, removing each element using the `Iterator.remove` operation.
boolean	contains(Object o) Returns `true` if this collection contains the specified element. This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
boolean	containsAll(Collection<?> c) Returns `true` if this collection contains all of the elements in the specified collection. This implementation iterates over the specified collection, checking each element returned by the iterator in turn to see if it's contained in this collection.
boolean	isEmpty() Returns `true` if this collection contains no elements. This implementation returns `size() == 0`.
abstract Iterator<E>	iterator() Returns an iterator over the elements contained in this collection.
boolean	remove(Object o) Removes a single instance of the specified element from this collection, if it is present (optional operation). This implementation iterates over the collection looking for the specified element.
boolean	removeAll(Collection<?> c) Removes all of this collection's elements that are also contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection.
boolean	retainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection.
abstract int	size() Returns the number of elements in this collection.
<T> T[]	toArray(T[] a) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. This implementation returns an array containing all the elements returned by this collection's iterator in the same order, stored in consecutive elements of the array, starting with index `0`.
Object[]	toArray() Returns an array containing all of the elements in this collection. This implementation returns an array containing all the elements returned by this collection's iterator, in the same order, stored in consecutive elements of the array, starting with index `0`.
String	toString() Returns a string representation of this collection.

From class java.lang.Object

Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>	getClass() Returns the runtime class of this `Object`.
int	hashCode() Returns a hash code value for the object.
final void	notify() Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll() Wakes up all threads that are waiting on this object's monitor.
String	toString() Returns a string representation of the object.
final void	wait() Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.
final void	wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.

From interface java.lang.Iterable

From interface java.util.Collection

abstract boolean	add(E e) Ensures that this collection contains the specified element (optional operation).
abstract boolean	addAll(Collection<? extends E> c) Adds all of the elements in the specified collection to this collection (optional operation).
abstract void	clear() Removes all of the elements from this collection (optional operation).
abstract boolean	contains(Object o) Returns `true` if this collection contains the specified element.
abstract boolean	containsAll(Collection<?> c) Returns `true` if this collection contains all of the elements in the specified collection.
abstract boolean	equals(Object o) Compares the specified object with this collection for equality.
abstract int	hashCode() Returns the hash code value for this collection.
abstract boolean	isEmpty() Returns `true` if this collection contains no elements.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this collection.
abstract boolean	remove(Object o) Removes a single instance of the specified element from this collection, if it is present (optional operation).
abstract boolean	removeAll(Collection<?> c) Removes all of this collection's elements that are also contained in the specified collection (optional operation).
abstract boolean	retainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation).
abstract int	size() Returns the number of elements in this collection.
abstract <T> T[]	toArray(T[] a) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
abstract Object[]	toArray() Returns an array containing all of the elements in this collection.

From interface java.util.Deque

abstract boolean	add(E e) Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and throwing an `IllegalStateException` if no space is currently available.
abstract void	addFirst(E e) Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions.
abstract void	addLast(E e) Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions.
abstract boolean	contains(Object o) Returns `true` if this deque contains the specified element.
abstract Iterator<E>	descendingIterator() Returns an iterator over the elements in this deque in reverse sequential order.
abstract E	element() Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque).
abstract E	getFirst() Retrieves, but does not remove, the first element of this deque.
abstract E	getLast() Retrieves, but does not remove, the last element of this deque.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this deque in proper sequence.
abstract boolean	offer(E e) Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and `false` if no space is currently available.
abstract boolean	offerFirst(E e) Inserts the specified element at the front of this deque unless it would violate capacity restrictions.
abstract boolean	offerLast(E e) Inserts the specified element at the end of this deque unless it would violate capacity restrictions.
abstract E	peek() Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returns `null` if this deque is empty.
abstract E	peekFirst() Retrieves, but does not remove, the first element of this deque, or returns `null` if this deque is empty.
abstract E	peekLast() Retrieves, but does not remove, the last element of this deque, or returns `null` if this deque is empty.
abstract E	poll() Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), or returns `null` if this deque is empty.
abstract E	pollFirst() Retrieves and removes the first element of this deque, or returns `null` if this deque is empty.
abstract E	pollLast() Retrieves and removes the last element of this deque, or returns `null` if this deque is empty.
abstract E	pop() Pops an element from the stack represented by this deque.
abstract void	push(E e) Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and throwing an `IllegalStateException` if no space is currently available.
abstract E	remove() Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque).
abstract boolean	remove(Object o) Removes the first occurrence of the specified element from this deque.
abstract E	removeFirst() Retrieves and removes the first element of this deque.
abstract boolean	removeFirstOccurrence(Object o) Removes the first occurrence of the specified element from this deque.
abstract E	removeLast() Retrieves and removes the last element of this deque.
abstract boolean	removeLastOccurrence(Object o) Removes the last occurrence of the specified element from this deque.
abstract int	size() Returns the number of elements in this deque.

From interface java.util.List

abstract boolean	add(E e) Appends the specified element to the end of this list (optional operation).
abstract void	add(int index, E element) Inserts the specified element at the specified position in this list (optional operation).
abstract 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 (optional operation).
abstract boolean	addAll(int index, Collection<? extends E> c) Inserts all of the elements in the specified collection into this list at the specified position (optional operation).
abstract void	clear() Removes all of the elements from this list (optional operation).
abstract boolean	contains(Object o) Returns `true` if this list contains the specified element.
abstract boolean	containsAll(Collection<?> c) Returns `true` if this list contains all of the elements of the specified collection.
abstract boolean	equals(Object o) Compares the specified object with this list for equality.
abstract E	get(int index) Returns the element at the specified position in this list.
abstract int	hashCode() Returns the hash code value for this list.
abstract int	indexOf(Object o) Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
abstract boolean	isEmpty() Returns `true` if this list contains no elements.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this list in proper sequence.
abstract int	lastIndexOf(Object o) Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
abstract ListIterator<E>	listIterator(int index) Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.
abstract ListIterator<E>	listIterator() Returns a list iterator over the elements in this list (in proper sequence).
abstract E	remove(int index) Removes the element at the specified position in this list (optional operation).
abstract boolean	remove(Object o) Removes the first occurrence of the specified element from this list, if it is present (optional operation).
abstract boolean	removeAll(Collection<?> c) Removes from this list all of its elements that are contained in the specified collection (optional operation).
abstract boolean	retainAll(Collection<?> c) Retains only the elements in this list that are contained in the specified collection (optional operation).
abstract E	set(int index, E element) Replaces the element at the specified position in this list with the specified element (optional operation).
abstract int	size() Returns the number of elements in this list.
abstract List<E>	subList(int fromIndex, int toIndex) Returns a view of the portion of this list between the specified `fromIndex`, inclusive, and `toIndex`, exclusive.
abstract <T> T[]	toArray(T[] a) Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.
abstract Object[]	toArray() Returns an array containing all of the elements in this list in proper sequence (from first to last element).

From interface java.util.Queue

Public Constructors

public LinkedList ()

Constructs an empty list.

public 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.

Parameters

c	the collection whose elements are to be placed into this list

Throws

NullPointerException	if the specified collection is null

Public Methods

public boolean add (E e)

Appends the specified element to the end of this list.

This method is equivalent to addLast(E).

Parameters

e	element to be appended to this list

Returns

true (as specified by add(E))

public void add (int index, E element)

Inserts the specified element at the specified position in this list. Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).

Parameters

index	index at which the specified element is to be inserted
element	element to be inserted

Throws

IndexOutOfBoundsException

public 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. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)

Parameters

c	collection containing elements to be added to this list

Returns

true if this list changed as a result of the call

Throws

NullPointerException	if the specified collection is null

public 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. Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in the list in the order that they are returned by the specified collection's iterator.

Parameters

index	index at which to insert the first element from the specified collection
c	collection containing elements to be added to this list

Returns

true if this list changed as a result of the call

Throws

IndexOutOfBoundsException
NullPointerException	if the specified collection is null

public void addFirst (E e)

Inserts the specified element at the beginning of this list.

Parameters

e	the element to add

public void addLast (E e)

Appends the specified element to the end of this list.

This method is equivalent to add(E).

Parameters

e	the element to add

public void clear ()

Removes all of the elements from this list.

public Object clone ()

Returns a shallow copy of this LinkedList. (The elements themselves are not cloned.)

Returns

a shallow copy of this LinkedList instance

public boolean contains (Object o)

Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that (o==null ? e==null : o.equals(e)).

Parameters

o	element whose presence in this list is to be tested

Returns

true if this list contains the specified element

public Iterator<E> descendingIterator ()

Returns an iterator over the elements in this deque in reverse sequential order. The elements will be returned in order from last (tail) to first (head).

Returns

an iterator over the elements in this deque in reverse sequence

public E element ()

Retrieves, but does not remove, the head (first element) of this list.

Returns

the head of this list

Throws

NoSuchElementException	if this list is empty

public E get (int index)

Returns the element at the specified position in this list.

Parameters

index	index of the element to return

Returns

the element at the specified position in this list

Throws

IndexOutOfBoundsException

public E getFirst ()

Returns the first element in this list.

Returns

the first element in this list

Throws

NoSuchElementException	if this list is empty

public E getLast ()

Returns the last element in this list.

Returns

the last element in this list

Throws

NoSuchElementException	if this list is empty

public int indexOf (Object o)

Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.

Parameters

o	element to search for

Returns

the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element

public int lastIndexOf (Object o)

Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest index i such that (o==null ? get(i)==null : o.equals(get(i))), or -1 if there is no such index.

Parameters

o	element to search for

Returns

the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element

public 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. Obeys the general contract of List.listIterator(int).

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 the 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

public boolean offer (E e)

Adds the specified element as the tail (last element) of this list.

Parameters

e	the element to add

Returns

true (as specified by offer(E))

public boolean offerFirst (E e)

Inserts the specified element at the front of this list.

Parameters

e	the element to insert

Returns

true (as specified by offerFirst(E))

public boolean offerLast (E e)

Inserts the specified element at the end of this list.

Parameters

e	the element to insert

Returns

true (as specified by offerLast(E))

public E peek ()

Retrieves, but does not remove, the head (first element) of this list.

Returns

the head of this list, or null if this list is empty

public E peekFirst ()

Retrieves, but does not remove, the first element of this list, or returns null if this list is empty.

Returns

the first element of this list, or null if this list is empty

public E peekLast ()

Retrieves, but does not remove, the last element of this list, or returns null if this list is empty.

Returns

the last element of this list, or null if this list is empty

public E poll ()

Retrieves and removes the head (first element) of this list

Returns

the head of this list, or null if this list is empty

public E pollFirst ()

Retrieves and removes the first element of this list, or returns null if this list is empty.

Returns

the first element of this list, or null if this list is empty

public E pollLast ()

Retrieves and removes the last element of this list, or returns null if this list is empty.

Returns

the last element of this list, or null if this list is empty

public E pop ()

Pops an element from the stack represented by this list. In other words, removes and returns the first element of this list.

This method is equivalent to removeFirst().

Returns

the element at the front of this list (which is the top of the stack represented by this list)

Throws

NoSuchElementException	if this list is empty

public void push (E e)

Pushes an element onto the stack represented by this list. In other words, inserts the element at the front of this list.

This method is equivalent to addFirst(E).

Parameters

e	the element to push

public E remove ()

Retrieves and removes the head (first element) of this list.

Returns

the head of this list

Throws

NoSuchElementException	if this list is empty

public E remove (int index)

Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.

Parameters

index	the index of the element to be removed

Returns

the element previously at the specified position

Throws

IndexOutOfBoundsException

public boolean remove (Object o)

Removes the first occurrence of the specified element from this list, if it is present. If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists). Returns true if this list contained the specified element (or equivalently, if this list changed as a result of the call).

Parameters

o	element to be removed from this list, if present

Returns

true if this list contained the specified element

public E removeFirst ()

Removes and returns the first element from this list.

Returns

the first element from this list

Throws

NoSuchElementException	if this list is empty

public boolean removeFirstOccurrence (Object o)

Removes the first occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not contain the element, it is unchanged.

Parameters

o	element to be removed from this list, if present

Returns

true if the list contained the specified element

public E removeLast ()

Removes and returns the last element from this list.

Returns

the last element from this list

Throws

NoSuchElementException	if this list is empty

public boolean removeLastOccurrence (Object o)

Removes the last occurrence of the specified element in this list (when traversing the list from head to tail). If the list does not contain the element, it is unchanged.

Parameters

o	element to be removed from this list, if present

Returns

true if the list contained the specified element

public E set (int index, E element)

Replaces the element at the specified position in this list with the specified element.

Parameters

index	index of the element to replace
element	element to be stored at the specified position

Returns

the element previously at the specified position

Throws

IndexOutOfBoundsException

public int size ()

Returns the number of elements in this list.

Returns

the number of elements in this list

public T[] toArray (T[] a)

Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.

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 list 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.)

Like the toArray() method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.

Suppose x is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array of String:

     String[] y = x.toArray(new String[0]);

Note that toArray(new Object[0]) is identical in function to toArray().

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 the specified array is not a supertype of the runtime type of every element in this list
NullPointerException	if the specified array is null

public Object[] toArray ()

Returns an array containing all of the elements in this list in proper sequence (from first to last element).

The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.

This method acts as bridge between array-based and collection-based APIs.

Returns

an array containing all of the elements in this list in proper sequence

Interfaces

Classes

Enums

Exceptions

Errors

LinkedList

Class Overview

See Also

Summary

Public Constructors

public LinkedList ()

public LinkedList (Collection<? extends E> c)

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Throws

Public Methods

public boolean add (E e)

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public void add (int index, E element)

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

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public boolean addAll (int index, Collection<? extends E> c)

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public void addFirst (E e)

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public void addLast (E e)

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public void clear ()

public Object clone ()

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public boolean contains (Object o)

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public Iterator<E> descendingIterator ()

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public E element ()

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public E get (int index)

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public E getFirst ()

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public E getLast ()

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public int indexOf (Object o)

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public int lastIndexOf (Object o)

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public ListIterator<E> listIterator (int index)

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See Also

public boolean offer (E e)

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public boolean offerFirst (E e)

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public boolean offerLast (E e)

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public E peek ()

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public E peekFirst ()

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public E peekLast ()

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