LinkedList (Java Platform SE 6) (original) (raw)
java.util
Class LinkedList
java.lang.Object
java.util.AbstractCollection
java.util.AbstractList
java.util.AbstractSequentialList
java.util.LinkedList
Type Parameters:
E - the type of elements held in this collection
All Implemented Interfaces:
Serializable, Cloneable, Iterable, Collection, Deque, List, Queue
public class LinkedList
extends AbstractSequentialList
implements List, Deque, Cloneable, Serializable
Linked list implementation of the List interface. Implements all optional list operations, and permits all elements (includingnull). In addition to implementing the List interface, the LinkedList class provides uniformly named methods toget, 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 theCollections.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 andlistIterator 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 oradd methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.
This class is a member of the Java Collections Framework.
Since:
1.2
See Also:
List, ArrayList, Vector, Serialized Form
| Field Summary |
|---|
| Fields inherited from class java.util.AbstractList |
|---|
| modCount |
| Constructor Summary |
|---|
| LinkedList() Constructs an empty list. |
| LinkedList(Collection<? extends E> c) Constructs a list containing the elements of the specified collection, in the order they are returned by the collection's iterator. |
| Method Summary | |
|---|---|
| boolean | add(E e) Appends the specified element to the end of this list. |
| void | [add](../../java/util/LinkedList.html#add%28int, E%29)(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](../../java/util/LinkedList.html#addAll%28int, java.util.Collection%29)(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](../../java/util/LinkedList.html#set%28int, E%29)(int index,E element) Replaces the element at the specified position in this list with the specified element. |
| int | size() Returns the number of elements in this list. |
| Object[] | toArray() Returns an array containing all of the elements in this list in proper sequence (from first to last element). |
| 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. |
| Methods inherited from class java.util.AbstractSequentialList |
|---|
| iterator |
| Methods inherited from class java.util.AbstractList |
|---|
| equals, hashCode, listIterator, [removeRange](../../java/util/AbstractList.html#removeRange%28int, int%29), [subList](../../java/util/AbstractList.html#subList%28int, int%29) |
| Methods inherited from class java.util.AbstractCollection |
|---|
| containsAll, isEmpty, removeAll, retainAll, toString |
| Methods inherited from class java.lang.Object |
|---|
| finalize, getClass, notify, notifyAll, wait, wait, [wait](../../java/lang/Object.html#wait%28long, int%29) |
| Methods inherited from interface java.util.List |
|---|
| containsAll, equals, hashCode, isEmpty, iterator, listIterator, removeAll, retainAll, [subList](../../java/util/List.html#subList%28int, int%29) |
| Methods inherited from interface java.util.Deque |
|---|
| iterator |
| Constructor Detail |
|---|
LinkedList
public LinkedList()
Constructs an empty list.
LinkedList
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](../../java/lang/NullPointerException.html "class in java.lang") - if the specified collection is null
| Method Detail |
|---|
getFirst
public E getFirst()
Returns the first element in this list.
Specified by:
[getFirst](../../java/util/Deque.html#getFirst%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the first element in this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
getLast
public E getLast()
Returns the last element in this list.
Specified by:
[getLast](../../java/util/Deque.html#getLast%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the last element in this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
removeFirst
public E removeFirst()
Removes and returns the first element from this list.
Specified by:
[removeFirst](../../java/util/Deque.html#removeFirst%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the first element from this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
removeLast
public E removeLast()
Removes and returns the last element from this list.
Specified by:
[removeLast](../../java/util/Deque.html#removeLast%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the last element from this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
addFirst
public void addFirst(E e)
Inserts the specified element at the beginning of this list.
Specified by:
[addFirst](../../java/util/Deque.html#addFirst%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to add
addLast
public void addLast(E e)
Appends the specified element to the end of this list.
This method is equivalent to add(E).
Specified by:
[addLast](../../java/util/Deque.html#addLast%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to add
contains
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)).
Specified by:
[contains](../../java/util/Collection.html#contains%28java.lang.Object%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[contains](../../java/util/Deque.html#contains%28java.lang.Object%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[contains](../../java/util/List.html#contains%28java.lang.Object%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[contains](../../java/util/AbstractCollection.html#contains%28java.lang.Object%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
o - element whose presence in this list is to be tested
Returns:
true if this list contains the specified element
size
public int size()
Returns the number of elements in this list.
Specified by:
[size](../../java/util/Collection.html#size%28%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[size](../../java/util/Deque.html#size%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[size](../../java/util/List.html#size%28%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[size](../../java/util/AbstractCollection.html#size%28%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the number of elements in this list
add
public boolean add(E e)
Appends the specified element to the end of this list.
This method is equivalent to addLast(E).
Specified by:
[add](../../java/util/Collection.html#add%28E%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[add](../../java/util/Deque.html#add%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[add](../../java/util/List.html#add%28E%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[add](../../java/util/Queue.html#add%28E%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[add](../../java/util/AbstractList.html#add%28E%29) in class [AbstractList](../../java/util/AbstractList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - element to be appended to this list
Returns:
true (as specified by Collection.add(E))
remove
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 indexi 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).
Specified by:
[remove](../../java/util/Collection.html#remove%28java.lang.Object%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[remove](../../java/util/Deque.html#remove%28java.lang.Object%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[remove](../../java/util/List.html#remove%28java.lang.Object%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[remove](../../java/util/AbstractCollection.html#remove%28java.lang.Object%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
o - element to be removed from this list, if present
Returns:
true if this list contained the specified element
addAll
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.)
Specified by:
[addAll](../../java/util/Collection.html#addAll%28java.util.Collection%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[addAll](../../java/util/List.html#addAll%28java.util.Collection%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[addAll](../../java/util/AbstractCollection.html#addAll%28java.util.Collection%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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](../../java/lang/NullPointerException.html "class in java.lang") - if the specified collection is null
See Also:
AbstractCollection.add(Object)
addAll
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.
Specified by:
[addAll](../../java/util/List.html#addAll%28int, java.util.Collection%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[addAll](../../java/util/AbstractSequentialList.html#addAll%28int, java.util.Collection%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index > size())
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified collection is null
clear
public void clear()
Removes all of the elements from this list.
Specified by:
[clear](../../java/util/Collection.html#clear%28%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[clear](../../java/util/List.html#clear%28%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[clear](../../java/util/AbstractList.html#clear%28%29) in class [AbstractList](../../java/util/AbstractList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
get
public E get(int index)
Returns the element at the specified position in this list.
Specified by:
[get](../../java/util/List.html#get%28int%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[get](../../java/util/AbstractSequentialList.html#get%28int%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
index - index of the element to return
Returns:
the element at the specified position in this list
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index >= size())
set
public E set(int index, E element)
Replaces the element at the specified position in this list with the specified element.
Specified by:
[set](../../java/util/List.html#set%28int, E%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[set](../../java/util/AbstractSequentialList.html#set%28int, E%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index >= size())
add
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).
Specified by:
[add](../../java/util/List.html#add%28int, E%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[add](../../java/util/AbstractSequentialList.html#add%28int, E%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
index - index at which the specified element is to be inserted
element - element to be inserted
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index > size())
remove
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.
Specified by:
[remove](../../java/util/List.html#remove%28int%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[remove](../../java/util/AbstractSequentialList.html#remove%28int%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
index - the index of the element to be removed
Returns:
the element previously at the specified position
Throws:
[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index >= size())
indexOf
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.
Specified by:
[indexOf](../../java/util/List.html#indexOf%28java.lang.Object%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[indexOf](../../java/util/AbstractList.html#indexOf%28java.lang.Object%29) in class [AbstractList](../../java/util/AbstractList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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
lastIndexOf
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.
Specified by:
[lastIndexOf](../../java/util/List.html#lastIndexOf%28java.lang.Object%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[lastIndexOf](../../java/util/AbstractList.html#lastIndexOf%28java.lang.Object%29) in class [AbstractList](../../java/util/AbstractList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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
peek
public E peek()
Retrieves, but does not remove, the head (first element) of this list.
Specified by:
[peek](../../java/util/Deque.html#peek%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[peek](../../java/util/Queue.html#peek%28%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the head of this list, or null if this list is empty
Since:
1.5
element
public E element()
Retrieves, but does not remove, the head (first element) of this list.
Specified by:
[element](../../java/util/Deque.html#element%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[element](../../java/util/Queue.html#element%28%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the head of this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
Since:
1.5
poll
public E poll()
Retrieves and removes the head (first element) of this list
Specified by:
[poll](../../java/util/Deque.html#poll%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[poll](../../java/util/Queue.html#poll%28%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the head of this list, or null if this list is empty
Since:
1.5
remove
public E remove()
Retrieves and removes the head (first element) of this list.
Specified by:
[remove](../../java/util/Deque.html#remove%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[remove](../../java/util/Queue.html#remove%28%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the head of this list
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
Since:
1.5
offer
public boolean offer(E e)
Adds the specified element as the tail (last element) of this list.
Specified by:
[offer](../../java/util/Deque.html#offer%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[offer](../../java/util/Queue.html#offer%28E%29) in interface [Queue](../../java/util/Queue.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to add
Returns:
true (as specified by Queue.offer(E))
Since:
1.5
offerFirst
public boolean offerFirst(E e)
Inserts the specified element at the front of this list.
Specified by:
[offerFirst](../../java/util/Deque.html#offerFirst%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to insert
Returns:
true (as specified by Deque.offerFirst(E))
Since:
1.6
offerLast
public boolean offerLast(E e)
Inserts the specified element at the end of this list.
Specified by:
[offerLast](../../java/util/Deque.html#offerLast%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to insert
Returns:
true (as specified by Deque.offerLast(E))
Since:
1.6
peekFirst
public E peekFirst()
Retrieves, but does not remove, the first element of this list, or returns null if this list is empty.
Specified by:
[peekFirst](../../java/util/Deque.html#peekFirst%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the first element of this list, or null if this list is empty
Since:
1.6
peekLast
public E peekLast()
Retrieves, but does not remove, the last element of this list, or returns null if this list is empty.
Specified by:
[peekLast](../../java/util/Deque.html#peekLast%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the last element of this list, or null if this list is empty
Since:
1.6
pollFirst
public E pollFirst()
Retrieves and removes the first element of this list, or returns null if this list is empty.
Specified by:
[pollFirst](../../java/util/Deque.html#pollFirst%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the first element of this list, or null if this list is empty
Since:
1.6
pollLast
public E pollLast()
Retrieves and removes the last element of this list, or returns null if this list is empty.
Specified by:
[pollLast](../../java/util/Deque.html#pollLast%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the last element of this list, or null if this list is empty
Since:
1.6
push
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).
Specified by:
[push](../../java/util/Deque.html#push%28E%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
e - the element to push
Since:
1.6
pop
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().
Specified by:
[pop](../../java/util/Deque.html#pop%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
the element at the front of this list (which is the top of the stack represented by this list)
Throws:
[NoSuchElementException](../../java/util/NoSuchElementException.html "class in java.util") - if this list is empty
Since:
1.6
removeFirstOccurrence
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.
Specified by:
[removeFirstOccurrence](../../java/util/Deque.html#removeFirstOccurrence%28java.lang.Object%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
o - element to be removed from this list, if present
Returns:
true if the list contained the specified element
Since:
1.6
removeLastOccurrence
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.
Specified by:
[removeLastOccurrence](../../java/util/Deque.html#removeLastOccurrence%28java.lang.Object%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Parameters:
o - element to be removed from this list, if present
Returns:
true if the list contained the specified element
Since:
1.6
listIterator
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 aConcurrentModificationException. 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.
Specified by:
[listIterator](../../java/util/List.html#listIterator%28int%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[listIterator](../../java/util/AbstractSequentialList.html#listIterator%28int%29) in class [AbstractSequentialList](../../java/util/AbstractSequentialList.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - if the index is out of range (index < 0 || index > size())
See Also:
descendingIterator
public Iterator<E> descendingIterator()
Description copied from interface: [Deque](../../java/util/Deque.html#descendingIterator%28%29)
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).
Specified by:
[descendingIterator](../../java/util/Deque.html#descendingIterator%28%29) in interface [Deque](../../java/util/Deque.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
an iterator over the elements in this deque in reverse sequence
Since:
1.6
clone
public Object clone()
Returns a shallow copy of this LinkedList. (The elements themselves are not cloned.)
Overrides:
[clone](../../java/lang/Object.html#clone%28%29) in class [Object](../../java/lang/Object.html "class in java.lang")
Returns:
a shallow copy of this LinkedList instance
See Also:
toArray
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.
Specified by:
[toArray](../../java/util/Collection.html#toArray%28%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[toArray](../../java/util/List.html#toArray%28%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[toArray](../../java/util/AbstractCollection.html#toArray%28%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Returns:
an array containing all of the elements in this list in proper sequence
See Also:
toArray
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 totoArray().
Specified by:
[toArray](../../java/util/Collection.html#toArray%28T[]%29) in interface [Collection](../../java/util/Collection.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Specified by:
[toArray](../../java/util/List.html#toArray%28T[]%29) in interface [List](../../java/util/List.html "interface in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
Overrides:
[toArray](../../java/util/AbstractCollection.html#toArray%28T[]%29) in class [AbstractCollection](../../java/util/AbstractCollection.html "class in java.util")<[E](../../java/util/LinkedList.html "type parameter in LinkedList")>
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](../../java/lang/ArrayStoreException.html "class in java.lang") - if the runtime type of the specified array is not a supertype of the runtime type of every element in this list
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified array is null
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