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CopyOnWriteArraySet empty = new CopyOnWriteArraySet();
Based on 33 examples
public class CopyOnWriteArraySet extends AbstractSet implements Serializable
A {@link java.util.Set} that uses an internal {@link CopyOnWriteArrayList} for all of its operations. Thus, it shares the same basic properties:
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<Handler>(); 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.
Constructor Summary | |
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Creates an empty set. |
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Creates a set containing all of the elements of the specified collection. |
Method Summary | |
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boolean |
Adds the specified element to this set if it is not already present. |
boolean |
addAll(Collection c) Adds all of the elements in the specified collection to this set if they're not already present. |
void |
clear() 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. |
boolean |
isEmpty() Returns true if this set contains no elements. |
Iterator |
iterator() 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 |
Retains only the elements in this set that are contained in the specified collection. |
int |
size() Returns the number of elements in this set. |
Object[] |
toArray() Returns an array containing all of the elements in this set. |
Object[] |
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.util.AbstractSet |
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equals, hashCode, removeAll |
Methods inherited from class java.util.AbstractCollection |
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add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public CopyOnWriteArraySet()
public CopyOnWriteArraySet(Collection c)
c
- the collection of elements to initially containMethod Detail |
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public boolean add(Object e)
add
in class AbstractCollection
e
- element to be added to this setpublic boolean addAll(Collection c)
addAll
in class AbstractCollection
c
- collection containing elements to be added to this setpublic void clear()
clear
in class AbstractCollection
public boolean contains(Object o)
contains
in class AbstractCollection
o
- element whose presence in this set is to be testedpublic boolean containsAll(Collection c)
containsAll
in class AbstractCollection
c
- collection to be checked for containment in this setpublic boolean equals(Object o)
equals
in class AbstractSet
o
- object to be compared for equality with this setpublic boolean isEmpty()
isEmpty
in class AbstractCollection
public Iterator iterator()
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.
iterator
in class AbstractCollection
public boolean remove(Object o)
remove
in class AbstractCollection
o
- object to be removed from this set, if presentpublic boolean removeAll(Collection c)
removeAll
in class AbstractSet
c
- collection containing elements to be removed from this setpublic boolean retainAll(Collection c)
retainAll
in class AbstractCollection
c
- collection containing elements to be retained in this setpublic int size()
size
in class AbstractCollection
public Object[] toArray()
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.
toArray
in class AbstractCollection
public Object[] toArray(Object[] a)
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 {@link #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().
toArray
in class AbstractCollection
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.
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