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| java.lang.Object
 java.util.concurrent.CopyOnWriteArrayList
| CopyOnWriteArrayList | | public class CopyOnWriteArrayList implements List<E>,RandomAccess,Cloneable,java.io.Serializable(Code) | | A thread-safe variant of
java.util.ArrayList in which all mutative
operations (add, set, and so on) are implemented by
making a fresh copy of the underlying array.
This is ordinarily too costly, but may be more efficient
than alternatives when traversal operations vastly outnumber
mutations, and is useful when you cannot or don't want to
synchronize traversals, yet need to preclude interference among
concurrent threads. The "snapshot" style iterator method uses a
reference to the state of the array at the point that the iterator
was created. This array never changes during the lifetime of the
iterator, so interference is impossible and the iterator is
guaranteed not to throw ConcurrentModificationException.
The iterator will not reflect additions, removals, or changes to
the list since the iterator was created. Element-changing
operations on iterators themselves (remove, set, and
add) are not supported. These methods throw
UnsupportedOperationException.
All elements are permitted, including null.
Memory consistency effects: As with other concurrent
collections, actions in a thread prior to placing an object into a
CopyOnWriteArrayList happen-before
actions subsequent to the access or removal of that element from
the
CopyOnWriteArrayList in another thread.
This class is a member of the
Java Collections Framework.
since:
1.5
author:
Doug Lea<
Parameters:
E - > the type of elements held in this collection |
| Method Summary | |
| public boolean | add(E e)
Appends the specified element to the end of this list. | | public void | add(int index, E element)
Inserts the specified element at the specified position in this
list. | | 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. | | 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. | | public int | addAllAbsent(Collection<? extends E> c)
Appends all of the elements in the specified collection that
are not already contained in this list, to the end of
this list, in the order that they are returned by the
specified collection's iterator. | | public boolean | addIfAbsent(E e)
Append the element if not present. | | public void | clear()
Removes all of the elements from this list. | | public Object | clone()
Returns a shallow copy of this list. | | public boolean | contains(Object o)
Returns true if this list contains the specified element. | | public boolean | containsAll(Collection c)
Returns true if this list contains all of the elements of the
specified collection. | | public boolean | equals(Object o)
Compares the specified object with this list for equality.
Returns
true if the specified object is the same object
as this object, or if it is also a
List and the sequence
of elements returned by an
over the specified list is the same as the sequence returned by
an iterator over this list. | | public E | get(int index)
| | final Object[] | getArray()
Gets the array. | | public int | hashCode()
Returns the hash code value for this list. | | public int | indexOf(Object o)
| | public int | indexOf(E e, int index)
Returns the index of the first occurrence of the specified element in
this list, searching forwards from index, or returns -1 if
the element is not found. | | public boolean | isEmpty()
Returns true if this list contains no elements. | | public Iterator<E> | iterator()
Returns an iterator over the elements in this list in proper sequence.
The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. | | public int | lastIndexOf(Object o)
| | public int | lastIndexOf(E e, int index)
Returns the index of the last occurrence of the specified element in
this list, searching backwards from index, or returns -1 if
the element is not found. | | public ListIterator<E> | listIterator()
The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. | | public ListIterator<E> | listIterator(int index)
The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. | | 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). | | public boolean | remove(Object o)
Removes the first occurrence of the specified element from this list,
if it is present. | | public boolean | removeAll(Collection c)
Removes from this list all of its elements that are contained in
the specified collection. | | public boolean | retainAll(Collection c)
Retains only the elements in this list that are contained in the
specified collection. | | public E | set(int index, E element)
Replaces the element at the specified position in this list with the
specified element. | | final void | setArray(Object[] a)
Sets the array. | | public int | size()
Returns the number of elements in this list. | | public List<E> | subList(int fromIndex, int toIndex)
Returns a view of the portion of this list between
fromIndex, inclusive, and toIndex, exclusive. | | 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. | | 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. | | public String | toString()
Returns a string representation of this list. |
| CopyOnWriteArrayList | | public CopyOnWriteArrayList()(Code) | | Creates an empty list.
|
| CopyOnWriteArrayList | | public CopyOnWriteArrayList(Collection<? extends E> c)(Code) | | Creates a list containing the elements of the specified
collection, in the order they are returned by the collection's
iterator.
Parameters:
c - the collection of initially held elements
throws:
NullPointerException - if the specified collection is null |
| CopyOnWriteArrayList | | public CopyOnWriteArrayList(E[] toCopyIn)(Code) | | Creates a list holding a copy of the given array.
Parameters:
toCopyIn - the array (a copy of this array is used as theinternal array)
throws:
NullPointerException - if the specified array is null |
| add | | public boolean add(E e)(Code) | | Appends the specified element to the end of this list.
Parameters:
e - element to be appended to this list true (as specified by Collection.add) |
| add | | public void add(int index, E element)(Code) | | 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).
throws:
IndexOutOfBoundsException - |
| addAll | | public boolean addAll(Collection<? extends E> c)(Code) | | 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.
Parameters:
c - collection containing elements to be added to this list true if this list changed as a result of the call
throws:
NullPointerException - if the specified collection is null
See Also: CopyOnWriteArrayList.add(Object) |
| addAll | | public boolean addAll(int index, Collection<? extends E> c)(Code) | | 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 this list in the order that they are returned by the
specified collection's iterator.
Parameters:
index - index at which to insert the first elementfrom the specified collection
Parameters:
c - collection containing elements to be added to this list true if this list changed as a result of the call
throws:
IndexOutOfBoundsException -
throws:
NullPointerException - if the specified collection is null
See Also: CopyOnWriteArrayList.add(int,Object) |
| addAllAbsent | | public int addAllAbsent(Collection<? extends E> c)(Code) | | Appends all of the elements in the specified collection that
are not already contained in this list, to the end of
this list, in the order that they are returned by the
specified collection's iterator.
Parameters:
c - collection containing elements to be added to this list the number of elements added
throws:
NullPointerException - if the specified collection is null
See Also: CopyOnWriteArrayList.addIfAbsent(Object) |
| addIfAbsent | | public boolean addIfAbsent(E e)(Code) | | Append the element if not present.
Parameters:
e - element to be added to this list, if absent true if the element was added |
| clear | | public void clear()(Code) | | Removes all of the elements from this list.
The list will be empty after this call returns.
|
| clone | | public Object clone()(Code) | | Returns a shallow copy of this list. (The elements themselves
are not copied.)
a clone of this list |
| contains | | public boolean contains(Object o)(Code) | | 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 true if this list contains the specified element |
| containsAll | | public boolean containsAll(Collection c)(Code) | | Returns true if this list contains all of the elements of the
specified collection.
Parameters:
c - collection to be checked for containment in this list true if this list contains all of the elements of thespecified collection
throws:
NullPointerException - if the specified collection is null
See Also: CopyOnWriteArrayList.contains(Object) |
| equals | | public boolean equals(Object o)(Code) | | Compares the specified object with this list for equality.
Returns
true if the specified object is the same object
as this object, or if it is also a
List and the sequence
of elements returned by an
over the specified list is the same as the sequence returned by
an iterator over this list. The two sequences are considered to
be the same if they have the same length and corresponding
elements at the same position in the sequence are equal.
Two elements
e1 and
e2 are considered
equal if
(e1==null ? e2==null : e1.equals(e2)) .
Parameters:
o - the object to be compared for equality with this list true if the specified object is equal to this list |
| getArray | | final Object[] getArray()(Code) | | Gets the array. Non-private so as to also be accessible
from CopyOnWriteArraySet class.
|
| hashCode | | public int hashCode()(Code) | | Returns the hash code value for this list.
This implementation uses the definition in
List.hashCode .
the hash code value for this list |
| indexOf | | public int indexOf(E e, int index)(Code) | | Returns the index of the first occurrence of the specified element in
this list, searching forwards from index, or returns -1 if
the element is not found.
More formally, returns the lowest index i such that
(i >= index && (e==null ? get(i)==null : e.equals(get(i)))),
or -1 if there is no such index.
Parameters:
e - element to search for
Parameters:
index - index to start searching from the index of the first occurrence of the element inthis list at position index or later in the list;-1 if the element is not found.
throws:
IndexOutOfBoundsException - if the specified index is negative |
| isEmpty | | public boolean isEmpty()(Code) | | Returns true if this list contains no elements.
true if this list contains no elements |
| iterator | | public Iterator<E> iterator()(Code) | | Returns an iterator over the elements in this list in proper sequence.
The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. No synchronization is needed while
traversing the iterator. The iterator does NOT support the
remove method.
an iterator over the elements in this list in proper sequence |
| lastIndexOf | | public int lastIndexOf(E e, int index)(Code) | | Returns the index of the last occurrence of the specified element in
this list, searching backwards from index, or returns -1 if
the element is not found.
More formally, returns the highest index i such that
(i <= index && (e==null ? get(i)==null : e.equals(get(i)))),
or -1 if there is no such index.
Parameters:
e - element to search for
Parameters:
index - index to start searching backwards from the index of the last occurrence of the element at positionless than or equal to index in this list;-1 if the element is not found.
throws:
IndexOutOfBoundsException - if the specified index is greaterthan or equal to the current size of this list |
| listIterator | | public ListIterator<E> listIterator()(Code) | | The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. No synchronization is needed while
traversing the iterator. The iterator does NOT support the
remove, set or add methods.
|
| listIterator | | public ListIterator<E> listIterator(int index)(Code) | | The returned iterator provides a snapshot of the state of the list
when the iterator was constructed. No synchronization is needed while
traversing the iterator. The iterator does NOT support the
remove, set or add methods.
throws:
IndexOutOfBoundsException - |
| remove | | public E remove(int index)(Code) | | 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.
throws:
IndexOutOfBoundsException - |
| remove | | public boolean remove(Object o)(Code) | | 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 true if this list contained the specified element |
| removeAll | | public boolean removeAll(Collection c)(Code) | | Removes from this list all of its elements that are contained in
the specified collection. This is a particularly expensive operation
in this class because of the need for an internal temporary array.
Parameters:
c - collection containing elements to be removed from this list true if this list changed as a result of the call
throws:
ClassCastException - if the class of an element of this listis incompatible with the specified collection (optional)
throws:
NullPointerException - if this list contains a null element and thespecified collection does not permit null elements (optional),or if the specified collection is null
See Also: CopyOnWriteArrayList.remove(Object) |
| retainAll | | public boolean retainAll(Collection c)(Code) | | Retains only the elements in this list that are contained in the
specified collection. In other words, removes from this list all of
its elements that are not contained in the specified collection.
Parameters:
c - collection containing elements to be retained in this list true if this list changed as a result of the call
throws:
ClassCastException - if the class of an element of this listis incompatible with the specified collection (optional)
throws:
NullPointerException - if this list contains a null element and thespecified collection does not permit null elements (optional),or if the specified collection is null
See Also: CopyOnWriteArrayList.remove(Object) |
| set | | public E set(int index, E element)(Code) | | Replaces the element at the specified position in this list with the
specified element.
throws:
IndexOutOfBoundsException - |
| setArray | | final void setArray(Object[] a)(Code) | | Sets the array.
|
| size | | public int size()(Code) | | Returns the number of elements in this list.
the number of elements in this list |
| subList | | public List<E> subList(int fromIndex, int toIndex)(Code) | | Returns a view of the portion of this list between
fromIndex, inclusive, and toIndex, exclusive.
The returned list is backed by this list, so changes in the
returned list are reflected in this list.
The semantics of the list returned by this method become
undefined if the backing list (i.e., this list) is modified in
any way other than via the returned list.
Parameters:
fromIndex - low endpoint (inclusive) of the subList
Parameters:
toIndex - high endpoint (exclusive) of the subList a view of the specified range within this list
throws:
IndexOutOfBoundsException - |
| toArray | | public Object[] toArray()(Code) | | 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.
an array containing all the elements in this list |
| toArray | | public T[] toArray(T a)(Code) | | 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 this list fits in the specified array with room to spare
(i.e., the array has more elements than this 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 this
list only if the caller knows that this list does not contain
any null elements.)
Like the
CopyOnWriteArrayList.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 tobe stored, if it is big enough; otherwise, a new array of thesame runtime type is allocated for this purpose. an array containing all the elements in this list
throws:
ArrayStoreException - if the runtime type of the specified arrayis not a supertype of the runtime type of every element inthis list
throws:
NullPointerException - if the specified array is null |
| toString | | public String toString()(Code) | | Returns a string representation of this list. The string
representation consists of the string representations of the list's
elements in the order they are returned by its iterator, enclosed in
square brackets ("[]"). Adjacent elements are separated by
the characters ", " (comma and space). Elements are
converted to strings as by
String.valueOf(Object) .
a string representation of this list |
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