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Class com.sun.java.util.collections.LinkedList
java.lang.Object
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+----com.sun.java.util.collections.AbstractCollection
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+----com.sun.java.util.collections.AbstractList
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+----com.sun.java.util.collections.AbstractSequentialList
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+----com.sun.java.util.collections.LinkedList
- public class LinkedList
- extends AbstractSequentialList
- implements List, Cloneable, Serializable
Linked list implementation of the List interface. Implements all
optional list operations, and permits all elements (including
null). In addition to implementing the List interface,
the LinkedList class provides uniformly named methods to
get, remove and insert an element at the
beginning and end of the list. These operations allow linked lists to be
used as a stack, queue, or double-ended queue (deque).
All of the stack/queue/deque operations could be easily recast in terms of
the standard list operations. They're included here primarily for
convenience, though they may run slightly faster than the equivalent List
operations.
All of the operations perform as could be expected for a doubly-linked
list. Operations that index into the list will traverse the list from
the begining or the end, whichever is closer to the specified index.
Note that this implementation is not synchronized. If multiple
threads access a list concurrently, and at least one of the threads
modifies the list structurally, it must be synchronized
externally. (A structural modification is any operation that adds or
deletes one or more elements; merely setting the value of an element is not
a structural modification.) This is typically accomplished by
synchronizing on some object that naturally encapsulates the list. If no
such object exists, the list should be "wrapped" using the
Collections.synchronizedList method. This is best done at creation time,
to prevent accidental unsynchronized access to the list:
List list = Collections.synchronizedList(new LinkedList(...));
The iterators returned by the this class's iterator and
listIterator methods are fail-fast: if the list is
structurally modified at any time after the iterator is created, in any way
except through the Iterator's own remove or add methods,
the iterator will throw a ConcurrentModificationException. Thus,
in the face of concurrent modification, the iterator fails quickly and
cleanly, rather than risking arbitrary, non-deterministic behavior at an
undetermined time in the future.
- See Also:
- List, ArrayList, Vector, synchronizedList
-
LinkedList()
- Constructs an empty list.
-
LinkedList(Collection)
- Constructs a list containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
-
add(int, Object)
- Inserts the specified element at the specified position in this list.
-
add(Object)
- Appends the specified element to the end of this list.
-
addAll(Collection)
- 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.
-
addAll(int, Collection)
- Inserts all of the elements in the specified collection into this
list, starting at the specified position.
-
addFirst(Object)
- Inserts the given element at the beginning of this list.
-
addLast(Object)
- Appends the given element to the end of this list.
-
clear()
- Removes all of the elements from this list.
-
clone()
- Returns a shallow copy of this LinkedList.
-
contains(Object)
- Returns true if this list contains the specified element.
-
get(int)
- Returns the element at the specified position in this list.
-
getFirst()
- Returns the first element in this list.
-
getLast()
- Returns the last element in this list.
-
indexOf(Object)
- Returns the index in this list of the first occurrence of the
specified element, or -1 if the List does not contain this
element.
-
lastIndexOf(Object)
- Returns the index in this list of the last occurrence of the
specified element, or -1 if the list does not contain this
element.
-
listIterator(int)
- Returns a list-iterator of the elements in this list (in proper
sequence), starting at the specified position in the list.
-
remove(int)
- Removes the element at the specified position in this list.
-
remove(Object)
- Removes the first occurrence of the specified element in this list.
-
removeFirst()
- Removes and returns the first element from this list.
-
removeLast()
- Removes and returns the last element from this list.
-
set(int, Object)
- Replaces the element at the specified position in this list with the
specified element.
-
size()
- Returns the number of elements in this list.
-
toArray()
- Returns an array containing all of the elements in this list
in the correct order.
-
toArray(Object[])
- Returns an array containing all of the elements in this list in
the correct order.
LinkedList
public LinkedList()
- Constructs an empty list.
LinkedList
public LinkedList(Collection c)
- Constructs a list containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
getFirst
public Object getFirst()
- Returns the first element in this list.
- Returns:
- the first element in this list.
getLast
public Object getLast()
- Returns the last element in this list.
- Returns:
- the last element in this list.
removeFirst
public Object removeFirst()
- Removes and returns the first element from this list.
- Returns:
- the first element from this list.
removeLast
public Object removeLast()
- Removes and returns the last element from this list.
- Returns:
- the last element from this list.
addFirst
public void addFirst(Object o)
- Inserts the given element at the beginning of this list.
addLast
public void addLast(Object o)
- Appends the given element to the end of this list. (Identical in
function to the add method; included only for consistency.)
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)).
- Parameters:
- o - element whose presence in this list is to be tested.
- Returns:
- true if this list contains the specified element.
- Overrides:
- contains in class AbstractCollection
size
public int size()
- Returns the number of elements in this list.
- Returns:
- the number of elements in this list.
- Overrides:
- size in class AbstractCollection
add
public boolean add(Object o)
- Appends the specified element to the end of this list.
- Parameters:
- o - element to be appended to this list.
- Returns:
- true (as per the general contract of
Collection.add).
- Overrides:
- add in class AbstractList
remove
public boolean remove(Object o)
- Removes the first occurrence of the specified element in this list. If
the 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).
- Parameters:
- o - element to be removed from this list, if present.
- Returns:
- true if the list contained the specified element.
- Overrides:
- remove in class AbstractCollection
addAll
public boolean addAll(Collection 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. (This implies that the behavior of this call is undefined if
the specified Collection is this list, and this list is nonempty.)
- Parameters:
- index - index at which to insert first element
from the specified collection.
- c - elements to be inserted into this list.
- Overrides:
- addAll in class AbstractCollection
addAll
public boolean addAll(int index,
Collection 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 first element
from the specified collection.
- c - elements to be inserted into this list.
- Overrides:
- addAll in class AbstractSequentialList
clear
public void clear()
- Removes all of the elements from this list.
- Overrides:
- clear in class AbstractList
get
public Object get(int index)
- Returns the element at the specified position in this list.
- Parameters:
- index - index of element to return.
- Returns:
- the element at the specified position in this list.
- Overrides:
- get in class AbstractSequentialList
set
public Object set(int index,
Object element)
- Replaces the element at the specified position in this list with the
specified element.
- Parameters:
- index - index of element to replace.
- element - element to be stored at the specified position.
- Returns:
- the element previously at the specified position.
- Overrides:
- set in class AbstractSequentialList
add
public void add(int index,
Object 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.
- Overrides:
- add in class AbstractSequentialList
remove
public Object 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 removed.
- Returns:
- the element previously at the specified position.
- Overrides:
- remove in class AbstractSequentialList
indexOf
public int indexOf(Object o)
- Returns the index in this list of the first occurrence of the
specified element, or -1 if the List does not contain this
element. 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 in this list of the first occurrence of the
specified element, or -1 if the list does not contain this
element.
- Overrides:
- indexOf in class AbstractList
lastIndexOf
public int lastIndexOf(Object o)
- Returns the index in this list of the last occurrence of the
specified element, or -1 if the list does not contain this
element. 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 in this list of the last occurrence of the
specified element, or -1 if the list does not contain this
element.
- Overrides:
- lastIndexOf in class AbstractList
listIterator
public ListIterator 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 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.
- Overrides:
- listIterator in class AbstractSequentialList
- See Also:
- listIterator
clone
public Object clone()
- Returns a shallow copy of this LinkedList. (The elements
themselves are not cloned.)
- Returns:
- a shallow copy of this LinkedList instance.
- Overrides:
- clone in class Object
toArray
public Object[] toArray()
- Returns an array containing all of the elements in this list
in the correct order.
- Returns:
- an array containing all of the elements in this list
in the correct order.
- Overrides:
- toArray in class AbstractCollection
toArray
public Object[] toArray(Object a[])
- Returns an array containing all of the elements in this list in
the correct order. The runtime type of the returned array is that of
the specified array. 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
collection is set to null. This is useful in determining the length
of the list only if the caller knows that the list
does not contain any null elements.
- 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.
- Overrides:
- toArray in class AbstractCollection
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