|
FlexDoc/Javadoc 2.0 Demo Java Doc |
Class CopyOnWriteArraySet<E>
java.util.concurrent.CopyOnWriteArraySet<E>
Type Parameters:
E - the type of elements held in this set
All Implemented Interfaces:
public class CopyOnWriteArraySet<E>
A
Set that uses an internal
CopyOnWriteArrayList
for all of its operations. Thus, it shares the same basic properties:
- It is best suited for applications in which set sizes generally
stay small, read-only operations
vastly outnumber mutative operations, and you need
to prevent interference among threads during traversal.
- It is thread-safe.
- Mutative operations (add, set, remove, etc.)
are expensive since they usually entail copying the entire underlying
array.
- Iterators do not support the mutative remove operation.
- Traversal via iterators is fast and cannot encounter
interference from other threads. Iterators rely on
unchanging snapshots of the array at the time the iterators were
constructed.
Sample Usage. The following code sketch uses a
copy-on-write set to maintain a set of Handler objects that
perform some action upon state updates.
class Handler { void handle() { ... } }
class X {
private final CopyOnWriteArraySet<Handler> handlers
= new CopyOnWriteArraySet<>();
public void addHandler(Handler h) { handlers.add(h); }
private long internalState;
private synchronized void changeState() { internalState = ...; }
public void update() {
changeState();
for (Handler handler : handlers)
handler.handle();
}
}
This class is a member of the
Java Collections Framework.
Since:
1.5
Author:
Doug Lea
See Also:
Constructor Summary |
Creates an empty set.
|
Creates a set containing all of the elements of the specified
collection.
|
Method Summary |
boolean |
Adds the specified element to this set if it is not already present.
|
boolean |
Adds all of the elements in the specified collection to this set if
they're not already present.
|
void |
Removes all of the elements from this set.
|
boolean |
Returns true if this set contains the specified element.
|
boolean |
Returns true if this set contains all of the elements of the
specified collection.
|
boolean |
Compares the specified object with this set for equality.
|
void |
Performs the given action for each element of the Iterable
until all elements have been processed or the action throws an
exception.
|
boolean |
Returns true if this set contains no elements.
|
|
Returns an iterator over the elements contained in this set
in the order in which these elements were added.
|
boolean |
Removes the specified element from this set if it is present.
|
boolean |
Removes from this set all of its elements that are contained in the
specified collection.
|
boolean |
Removes all of the elements of this collection that satisfy the given
predicate.
|
boolean |
Retains only the elements in this set that are contained in the
specified collection.
|
int |
Returns the number of elements in this set.
|
|
Returns a Spliterator over the elements in this set in the order
in which these elements were added.
|
|
Returns an array containing all of the elements in this set.
|
|
Returns an array containing all of the elements in this set; the
runtime type of the returned array is that of the specified array.
|
Methods inherited from class java.lang. Object |
|
Methods inherited from interface java.util. Collection |
|
Methods inherited from interface java.util. Set |
copyOf, of, of, of, of, of, of, of, of, of, of, of, of |
public CopyOnWriteArraySet |
() |
Creates an empty set.
public CopyOnWriteArraySet |
|
Creates a set containing all of the elements of the specified
collection.
Parameters:
c - the collection of elements to initially contain
Throws:
Returns the number of elements in this set.
Specified by:
Overrides:
Returns:
the number of elements in this set
public boolean isEmpty |
() |
Returns
true if this set contains no elements.
Specified by:
Overrides:
Returns:
true if this set contains no elements
Returns
true if this set contains the specified element.
More formally, returns
true if and only if this set
contains an element
e such that
Objects.equals(o, e).
Specified by:
Overrides:
Parameters:
o - element whose presence in this set is to be tested
Returns:
true if this set contains the specified element
Returns an array containing all of the elements in this set.
If this set makes any guarantees as to what order its elements
are returned by its iterator, this method must return the
elements in the same order.
The returned array will be "safe" in that no references to it
are maintained by this set. (In other words, this method must
allocate a new array even if this set is backed by an 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:
Overrides:
Returns:
an array containing all the elements in this set
Returns an array containing all of the elements in this set; the
runtime type of the returned array is that of the specified array.
If the set 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 set.
If this set fits in the specified array with room to spare
(i.e., the array has more elements than this set), the element in
the array immediately following the end of the set is set to
null. (This is useful in determining the length of this
set only if the caller knows that this set does not contain
any null elements.)
If this set makes any guarantees as to what order its elements
are returned by its iterator, this method must return the elements
in the same order.
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 set known to contain only strings.
The following code can be used to dump the set 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().
Specified by:
Overrides:
Type Parameters:
T - the component type of the array to contain the collection
Parameters:
a - the array into which the elements of this set 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 all the elements in this set
Throws:
ArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in this
set
Removes all of the elements from this set.
The set will be empty after this call returns.
Specified by:
Overrides:
Removes the specified element from this set if it is present.
More formally, removes an element
e such that
Objects.equals(o, e), if this set contains such an element.
Returns
true if this set contained the element (or
equivalently, if this set changed as a result of the call).
(This set will not contain the element once the call returns.)
Specified by:
Overrides:
Parameters:
o - object to be removed from this set, if present
Returns:
true if this set contained the specified element
Adds the specified element to this set if it is not already present.
More formally, adds the specified element
e to this set if
the set contains no element
e2 such that
Objects.equals(e, e2).
If this set already contains the element, the call leaves the set
unchanged and returns
false.
Specified by:
Overrides:
Parameters:
e - element to be added to this set
Returns:
true if this set did not already contain the specified
element
public boolean containsAll |
|
Returns
true if this set contains all of the elements of the
specified collection. If the specified collection is also a set, this
method returns
true if it is a
subset of this set.
Specified by:
Overrides:
Parameters:
c - collection to be checked for containment in this set
Returns:
true if this set contains all of the elements of the
specified collection
Throws:
See Also:
Adds all of the elements in the specified collection to this set if
they're not already present. If the specified collection is also a
set, the
addAll operation effectively modifies this set so
that its value is the
union of the two sets. The behavior of
this operation is undefined if the specified collection is modified
while the operation is in progress.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be added to this set
Returns:
true if this set changed as a result of the call
Throws:
See Also:
Removes from this set all of its elements that are contained in the
specified collection. If the specified collection is also a set,
this operation effectively modifies this set so that its value is the
asymmetric set difference of the two sets.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be removed from this set
Returns:
true if this set changed as a result of the call
Throws:
ClassCastException - if the class of an element of this set
is incompatible with the specified collection
(
optional)
NullPointerException - if this set contains a null element and the
specified collection does not permit null elements
(
optional),
or if the specified collection is null
See Also:
Retains only the elements in this set that are contained in the
specified collection. In other words, removes from this set all of
its elements that are not contained in the specified collection. If
the specified collection is also a set, this operation effectively
modifies this set so that its value is the
intersection of the
two sets.
Specified by:
Overrides:
Parameters:
c - collection containing elements to be retained in this set
Returns:
true if this set changed as a result of the call
Throws:
ClassCastException - if the class of an element of this set
is incompatible with the specified collection
(
optional)
NullPointerException - if this set contains a null element and the
specified collection does not permit null elements
(
optional),
or if the specified collection is null
See Also:
Returns an iterator over the elements contained in this set
in the order in which these elements were added.
The returned iterator provides a snapshot of the state of the set
when the iterator was constructed. No synchronization is needed while
traversing the iterator. The iterator does NOT support the
remove method.
Specified by:
Overrides:
Returns:
an iterator over the elements in this set
Compares the specified object with this set for equality.
Returns
true if the specified object is the same object
as this object, or if it is also a
Set and the elements
returned by an
iterator over the
specified set are the same as the elements returned by an
iterator over this set. More formally, the two iterators are
considered to return the same elements if they return the same
number of elements and for every element
e1 returned by
the iterator over the specified set, there is an element
e2 returned by the iterator over this set such that
Objects.equals(e1, e2).
Specified by:
Overrides:
Parameters:
o - object to be compared for equality with this set
Returns:
true if the specified object is equal to this set
See Also:
Removes all of the elements of this collection that satisfy the given
predicate. Errors or runtime exceptions thrown during iteration or by
the predicate are relayed to the caller.
Specified by:
Parameters:
filter - a predicate which returns true for elements to be
removed
Returns:
true if any elements were removed
Throws:
Description copied from interface:
Iterable
Performs the given action for each element of the
Iterable
until all elements have been processed or the action throws an
exception. Actions are performed in the order of iteration, if that
order is specified. Exceptions thrown by the action are relayed to the
caller.
The behavior of this method is unspecified if the action performs
side-effects that modify the underlying source of elements, unless an
overriding class has specified a concurrent modification policy.
Specified by:
Parameters:
action - The action to be performed for each element
Throws:
Returns a
Spliterator over the elements in this set in the order
in which these elements were added.
The Spliterator reports Spliterator.IMMUTABLE,
Spliterator.DISTINCT, Spliterator.SIZED, and
Spliterator.SUBSIZED.
The spliterator provides a snapshot of the state of the set
when the spliterator was constructed. No synchronization is needed while
operating on the spliterator.
Specified by:
Returns:
a Spliterator over the elements in this set
Since:
1.8
|
FlexDoc/Javadoc 2.0 Demo Java Doc |
FlexDoc/Javadoc is a template-driven programming tool for rapid development of any Javadoc-based Java API documentation generators (i.e. doclets). If you need to customize your Javadoc without writing a full-blown doclet from scratch,
FlexDoc/Javadoc may be the only tool able to help you! Find out more at
www.flexdoc.xyz