public class LinkedList<E>

  1. Object
  2. AbstractCollection<E>
  3. AbstractList<E>
  4. AbstractSequentialList<E>
  5. LinkedList

ImplementsCollection<E>, Deque<E>, Iterable<E>, List<E>, Queue<E>

LinkedList is an implementation of List, backed by a linked list. All optional operations are supported, adding, removing and replacing. The elements can be any objects.

Constructors

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

Methods

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

Inherited fields

From AbstractList

modCount

Inherited methods

From AbstractSequentialList

iterator

From AbstractList

equals, hashCode, listIterator, removeRange, subList

From AbstractCollection

containsAll, isEmpty, removeAll, retainAll, toString

From Object

getClass, notify, notifyAll, wait, wait, wait, clone

From Collection

removeIf

From Iterable

forEach

From List

replaceAll, sort

Constructor details

LinkedList

public LinkedList()
Constructs a new empty instance of LinkedList.

LinkedList

public LinkedList(Collection<? extends E> collection)
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 Collection<? extends E>
the collection of elements to add.

Method details

add

public void add(int location, E object)
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 int
the index at which to insert.
object E
the object to add.

Throws

IndexOutOfBoundsException
if location = size()
UnsupportedOperationException
if adding to this List is not supported.
ClassCastException
if the class of the object is inappropriate for this List
IllegalArgumentException
if the object cannot be added to this List

add

public boolean add(E object)
Adds the specified object at the end of this LinkedList.

Parameters

object E
the object to add.

Returns

always true

addAll

public boolean addAll(int location, Collection<? extends E> collection)
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 int
the index at which to insert.
collection Collection<? extends E>
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 size()

addAll

public boolean addAll(Collection<? extends E> collection)
Adds the objects in the specified Collection to this LinkedList.

Parameters

collection Collection<? extends E>
the collection of objects.

Returns

true if this LinkedList is modified, false otherwise.

addFirst

public void addFirst(E object)
Adds the specified object at the beginning of this LinkedList.

Parameters

object E
the object to add.

Throws

IllegalStateException
if it can not add now due to size limit
ClassCastException
if the class of element can not be added into this deque
NullPointerException
if the element is null and the deque can not contain null element
IllegalArgumentException
if the element can not be added due to some property.

addLast

public void addLast(E object)
Adds the specified object at the end of this LinkedList.

Parameters

object E
the object to add.

Throws

IllegalStateException
if it can not add now due to size limit
ClassCastException
if the class of element can not be added into this deque
NullPointerException
if the element is null and the deque can not contain null element
IllegalArgumentException
if the element can not be added due to some property.

clear

public void clear()
Removes all elements from this LinkedList, leaving it empty.

Throws

UnsupportedOperationException
if removing from this list is not supported.

See also

contains

public boolean contains(Object object)
Searches this LinkedList for the specified object.

Parameters

object Object
the object to search for.

Returns

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

get

public E get(int location)
Returns the element at the specified location in this list.

Parameters

location int
the index of the element to return.

Returns

the element at the specified index.

Throws

IndexOutOfBoundsException
if location = size()

getFirst

public E getFirst()
Returns the first element in this LinkedList.

Returns

the first element.

Throws

NoSuchElementException
if this LinkedList is empty.

getLast

public E getLast()
Returns the last element in this LinkedList.

Returns

the last element

Throws

NoSuchElementException
if this LinkedList is empty

indexOf

public int indexOf(Object object)
Searches this list for the specified object and returns the index of the first occurrence.

Parameters

object Object
the object to search for.

Returns

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

lastIndexOf

public int lastIndexOf(Object object)
Searches this LinkedList for the specified object and returns the index of the last occurrence.

Parameters

object Object
the object to search for

Returns

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

listIterator

public ListIterator<E> listIterator(int location)
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 int
the index at which to start the iteration

Returns

a ListIterator on the elements of this LinkedList

Throws

IndexOutOfBoundsException
if location = size()

See also

remove

public E remove(int location)
Removes the object at the specified location from this LinkedList.

Parameters

location int
the index of the object to remove

Returns

the removed object

Throws

IndexOutOfBoundsException
if location = size()

remove

public boolean remove(Object object)
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 Object
the object to remove.

Returns

true if this Collection is modified, false otherwise.

Throws

UnsupportedOperationException
if removing from this Collection is not supported.
ClassCastException
if the object passed is not of the correct type.
NullPointerException
if object is null and this Collection doesn’t support null elements.

removeFirst

public E removeFirst()
Removes the first object from this LinkedList.

Returns

the removed object.

Throws

NoSuchElementException
if this LinkedList is empty.

removeLast

public E removeLast()
Removes the last object from this LinkedList.

Returns

the removed object.

Throws

NoSuchElementException
if this LinkedList is empty.

descendingIterator

public Iterator<E> descendingIterator()
Returns the iterator in reverse order, from tail to head.

Returns

the iterator in reverse order

See also

offerFirst

public boolean offerFirst(E e)
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 E
the element

Returns

true if the operation succeeds or false if it fails.

Throws

ClassCastException
if the class of element can not be added into this deque
NullPointerException
if the element is null and the deque can not contain null element
IllegalArgumentException
if the element can not be added due to some property.

See also

offerLast

public boolean offerLast(E e)
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 E
the element

Returns

true if the operation succeeds or false if it fails

Throws

ClassCastException
if the class of element can not be added into this deque
NullPointerException
if the element is null and the deque can not contain null element
IllegalArgumentException
if the element can not be added due to some property

See also

peekFirst

public E peekFirst()
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

See also

peekLast

public E peekLast()
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

See also

pollFirst

public E pollFirst()
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

See also

pollLast

public E pollLast()
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

See also

pop

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

Returns

the head element

Throws

NoSuchElementException
if the deque is empty

See also

push

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

Parameters

e E
the element

Throws

IllegalStateException
if it can not add now due to size limit
ClassCastException
if the class of element can not be added into this deque
NullPointerException
if the element is null and the deque can not contain null element
IllegalArgumentException
if the element can not be added due to some property.

See also

removeFirstOccurrence

public boolean removeFirstOccurrence(Object o)
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 Object
the element to be removed

Returns

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

Throws

ClassCastException
if the class of the element is incompatible with the deque
NullPointerException
if the element is null and the deque can not contain null element

See also

removeLastOccurrence

public boolean removeLastOccurrence(Object o)
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 Object
the element to be removed

Returns

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

Throws

ClassCastException
if the class of the element is incompatible with the deque
NullPointerException
if the element is null and the deque can not contain null element

See also

set

public E set(int location, E object)
Replaces the element at the specified location in this LinkedList with the specified object.

Parameters

location int
the index at which to put the specified object.
object E
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 = size()

size

public int size()
Returns the number of elements in this LinkedList.

Returns

the number of elements in this LinkedList.

offer

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

Parameters

o E
the specified element to insert into the queue.

Returns

true if the operation succeeds and false if it fails.

poll

public E poll()
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.

remove

public E remove()
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.

Throws

NoSuchElementException
if there is no element in the queue.

peek

public E peek()
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.

element

public E element()
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.

Throws

NoSuchElementException
if there is no element in the queue.

toArray

public Object[] toArray()
Returns a new array containing all elements contained in this LinkedList.

Returns

an array of the elements from this LinkedList.

toArray

public <T> T[] toArray(T[] contents)
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 T[]
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.