Apache Commons Collections 4.4 · org.apache.commons.collections4.collection.SynchronizedCollection

Modifier and Type	Field and Description
private final Collection<E>	collection The collection to decorate
protected final Object	lock The object to lock on, needed for List/SortedSet views
private static final long	serialVersionUID Serialization version

Access	Constructor and Description
protected	SynchronizedCollection(final Collection<E> the collection to decorate, must not be null collection) Constructor that wraps (not copies).
protected	SynchronizedCollection(final Collection<E> the collection to decorate, must not be null collection, final Object the lock object to use, must not be null lock) Constructor that wraps (not copies).

Method Summary

Modifier and Type	Method and Description
public boolean	add(final E element whose presence in this collection is to be ensured object) Implements java.util.Collection.add. Ensures that this collection contains the specified element (optional operation).
public boolean	addAll(final Collection<? extends E> collection containing elements to be added to this collection coll) Implements java.util.Collection.addAll. Adds all of the elements in the specified collection to this collection (optional operation).
public void	clear() Implements java.util.Collection.clear. Removes all of the elements from this collection (optional operation).
public boolean	contains(final Object element whose presence in this collection is to be tested object) Implements java.util.Collection.contains. Returns `true` if this collection contains the specified element.
public boolean	containsAll(final Collection<?> collection to be checked for containment in this collection coll) Implements java.util.Collection.containsAll. Returns `true` if this collection contains all of the elements in the specified collection.
protected Collection<E>	Returns: the decorated collection decorated() Gets the collection being decorated.
public boolean	equals(final Object object to be compared for equality with this collection object) Overrides java.lang.Object.equals. Implements java.util.Collection.equals. Compares the specified object with this collection for equality.
public int	hashCode() Overrides java.lang.Object.hashCode. Implements java.util.Collection.hashCode. Returns the hash code value for this collection.
public boolean	isEmpty() Implements java.util.Collection.isEmpty. Returns `true` if this collection contains no elements.
public Iterator<E>	Returns: an iterator that must be manually synchronized on the collection iterator() Implements java.util.Collection.iterator. Iterators must be manually synchronized.
public boolean	remove(final Object element to be removed from this collection, if present object) Implements java.util.Collection.remove. Removes a single instance of the specified element from this collection, if it is present (optional operation).
public boolean	removeAll(final Collection<?> collection containing elements to be removed from this collection coll) Implements java.util.Collection.removeAll. Removes all of this collection's elements that are also contained in the specified collection (optional operation).
public boolean	removeIf(final Predicate<? super E> a predicate which returns `true` for elements to be removed filter) Overrides default java.util.Collection.removeIf. Removes all of the elements of this collection that satisfy the given predicate.
public boolean	retainAll(final Collection<?> collection containing elements to be retained in this collection coll) Implements java.util.Collection.retainAll. Retains only the elements in this collection that are contained in the specified collection (optional operation).
public int	size() Implements java.util.Collection.size. Returns the number of elements in this collection.
public static < the type of the elements in the collection T> SynchronizedCollection<T>	Returns: a new synchronized collection synchronizedCollection(final Collection<T> the collection to decorate, must not be null coll) Factory method to create a synchronized collection.
public Object[]	toArray() Implements java.util.Collection.toArray. Returns an array containing all of the elements in this collection.
public <T> T[]	toArray(final T[] the array into which the elements of this collection are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose. object) Implements java.util.Collection.toArray. Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.

Inherited from java.lang.Object:: clone finalize getClass notify notifyAll wait wait wait

collection	back to summary
private final Collection<E> collection The collection to decorate

lock	back to summary
protected final Object lock The object to lock on, needed for List/SortedSet views

serialVersionUID	back to summary
private static final long serialVersionUID Serialization version

SynchronizedCollection	back to summary
protected SynchronizedCollection(final Collection<E> collection) Constructor that wraps (not copies). Parameters collection:Collection<E> the collection to decorate, must not be null Exceptions NullPointerException: if the collection is null

SynchronizedCollection	back to summary
protected SynchronizedCollection(final Collection<E> collection, final Object lock) Constructor that wraps (not copies). Parameters collection:Collection<E> the collection to decorate, must not be null lock:Object the lock object to use, must not be null Exceptions NullPointerException: if the collection or lock is null

Method Detail

add back to summary

add	back to summary
public boolean add(final E object) Implements java.util.Collection.add. Doc from java.util.Collection.add. Ensures that this collection contains the specified element (optional operation). Returns `true` if this collection changed as a result of the call. (Returns `false` if this collection does not permit duplicates and already contains the specified element.) Collections that support this operation may place limitations on what elements may be added to this collection. In particular, some collections will refuse to add `null` elements, and others will impose restrictions on the type of elements that may be added. Collection classes should clearly specify in their documentation any restrictions on what elements may be added. If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw an exception (rather than returning `false`). This preserves the invariant that a collection always contains the specified element after this call returns. Parameters object:E element whose presence in this collection is to be ensured Returns:boolean `true` if this collection changed as a result of the call Annotations @Override

public boolean add(final E object)

Implements java.util.Collection.add.

Doc from java.util.Collection.add.

Ensures that this collection contains the specified element (optional operation). Returns true if this collection changed as a result of the call. (Returns false if this collection does not permit duplicates and already contains the specified element.)

Collections that support this operation may place limitations on what elements may be added to this collection. In particular, some collections will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. Collection classes should clearly specify in their documentation any restrictions on what elements may be added.

If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw an exception (rather than returning false). This preserves the invariant that a collection always contains the specified element after this call returns.

Parameters

object:E: element whose presence in this collection is to be ensured

Returns:boolean

true if this collection changed as a result of the call

Annotations

@Override

addAll back to summary

addAll	back to summary
public boolean addAll(final Collection<? extends E> coll) Implements java.util.Collection.addAll. Doc from java.util.Collection.addAll. Adds all of the elements in the specified collection to this collection (optional operation). 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 collection, and this collection is nonempty.) If the specified collection has a defined encounter order, processing of its elements generally occurs in that order. Parameters coll:Collection<? extends E> collection containing elements to be added to this collection Returns:boolean `true` if this collection changed as a result of the call Annotations @Override

public boolean addAll(final Collection<? extends E> coll)

Implements java.util.Collection.addAll.

Doc from java.util.Collection.addAll.

Adds all of the elements in the specified collection to this collection (optional operation). 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 collection, and this collection is nonempty.) If the specified collection has a defined encounter order, processing of its elements generally occurs in that order.

Parameters

coll:Collection<? extends E>: collection containing elements to be added to this collection

Returns:boolean

true if this collection changed as a result of the call

Annotations

@Override

clear	back to summary
public void clear() Implements java.util.Collection.clear. Doc from java.util.Collection.clear. Removes all of the elements from this collection (optional operation). The collection will be empty after this method returns. Annotations @Override

clear

back to summary

public void clear()

Implements java.util.Collection.clear.

Doc from java.util.Collection.clear.

Removes all of the elements from this collection (optional operation). The collection will be empty after this method returns.

Annotations

@Override

contains back to summary

contains	back to summary
public boolean contains(final Object object) Implements java.util.Collection.contains. Doc from java.util.Collection.contains. Returns `true` if this collection contains the specified element. More formally, returns `true` if and only if this collection contains at least one element `e` such that `Objects.equals(o, e)`. Parameters object:Object element whose presence in this collection is to be tested Returns:boolean `true` if this collection contains the specified element Annotations @Override

public boolean contains(final Object object)

Implements java.util.Collection.contains.

Doc from java.util.Collection.contains.

Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that Objects.equals(o, e).

Parameters

object:Object: element whose presence in this collection is to be tested

Returns:boolean

true if this collection contains the specified element

Annotations

@Override

containsAll back to summary

containsAll	back to summary
public boolean containsAll(final Collection<?> coll) Implements java.util.Collection.containsAll. Doc from java.util.Collection.containsAll. Returns `true` if this collection contains all of the elements in the specified collection. Parameters coll:Collection<?> collection to be checked for containment in this collection Returns:boolean `true` if this collection contains all of the elements in the specified collection Annotations @Override

public boolean containsAll(final Collection<?> coll)

Implements java.util.Collection.containsAll.

Doc from java.util.Collection.containsAll.

Returns true if this collection contains all of the elements in the specified collection.

Parameters

coll:Collection<?>: collection to be checked for containment in this collection

Returns:boolean

true if this collection contains all of the elements in the specified collection

Annotations

@Override

decorated	back to summary
protected Collection<E> decorated() Gets the collection being decorated. Returns:Collection<E> the decorated collection

decorated

back to summary

protected Collection<E> decorated()

Gets the collection being decorated.

Returns:Collection<E>: the decorated collection

equals back to summary

equals	back to summary
public boolean equals(final Object object) Overrides java.lang.Object.equals. Implements java.util.Collection.equals. Doc from java.util.Collection.equals. Compares the specified object with this collection for equality. While the `Collection` interface adds no stipulations to the general contract for the `Object.equals`, programmers who implement the `Collection` interface "directly" (in other words, create a class that is a `Collection` but is not a `Set` or a `List`) must exercise care if they choose to override the `Object.equals`. It is not necessary to do so, and the simplest course of action is to rely on `Object`'s implementation, but the implementor may wish to implement a "value comparison" in place of the default "reference comparison." (The `List` and `Set` interfaces mandate such value comparisons.) The general contract for the `Object.equals` method states that equals must be symmetric (in other words, `a.equals(b)` if and only if `b.equals(a)`). The contracts for `List.equals` and `Set.equals` state that lists are only equal to other lists, and sets to other sets. Thus, a custom `equals` method for a collection class that implements neither the `List` nor `Set` interface must return `false` when this collection is compared to any list or set. (By the same logic, it is not possible to write a class that correctly implements both the `Set` and `List` interfaces.) Parameters object:Object object to be compared for equality with this collection Returns:boolean `true` if the specified object is equal to this collection Annotations @Override

public boolean equals(final Object object)

Overrides java.lang.Object.equals.

Implements java.util.Collection.equals.

Doc from java.util.Collection.equals.

Compares the specified object with this collection for equality.

While the Collection interface adds no stipulations to the general contract for the Object.equals, programmers who implement the Collection interface "directly" (in other words, create a class that is a Collection but is not a Set or a List) must exercise care if they choose to override the Object.equals. It is not necessary to do so, and the simplest course of action is to rely on Object's implementation, but the implementor may wish to implement a "value comparison" in place of the default "reference comparison." (The List and Set interfaces mandate such value comparisons.)

The general contract for the Object.equals method states that equals must be symmetric (in other words, a.equals(b) if and only if b.equals(a)). The contracts for List.equals and Set.equals state that lists are only equal to other lists, and sets to other sets. Thus, a custom equals method for a collection class that implements neither the List nor Set interface must return false when this collection is compared to any list or set. (By the same logic, it is not possible to write a class that correctly implements both the Set and List interfaces.)

Parameters

object:Object: object to be compared for equality with this collection

Returns:boolean

true if the specified object is equal to this collection

Annotations

@Override

hashCode back to summary

hashCode	back to summary
public int hashCode() Overrides java.lang.Object.hashCode. Implements java.util.Collection.hashCode. Doc from java.util.Collection.hashCode. Returns the hash code value for this collection. While the `Collection` interface adds no stipulations to the general contract for the `Object.hashCode` method, programmers should take note that any class that overrides the `Object.equals` method must also override the `Object.hashCode` method in order to satisfy the general contract for the `Object.hashCode` method. In particular, `c1.equals(c2)` implies that `c1.hashCode()==c2.hashCode()`. Returns:int the hash code value for this collection Annotations @Override

public int hashCode()

Overrides java.lang.Object.hashCode.

Implements java.util.Collection.hashCode.

Doc from java.util.Collection.hashCode.

Returns the hash code value for this collection. While the Collection interface adds no stipulations to the general contract for the Object.hashCode method, programmers should take note that any class that overrides the Object.equals method must also override the Object.hashCode method in order to satisfy the general contract for the Object.hashCode method. In particular, c1.equals(c2) implies that c1.hashCode()==c2.hashCode().

Returns:int

the hash code value for this collection

Annotations

@Override

isEmpty back to summary

isEmpty	back to summary
public boolean isEmpty() Implements java.util.Collection.isEmpty. Doc from java.util.Collection.isEmpty. Returns `true` if this collection contains no elements. Returns:boolean `true` if this collection contains no elements Annotations @Override

public boolean isEmpty()

Implements java.util.Collection.isEmpty.

Doc from java.util.Collection.isEmpty.

Returns true if this collection contains no elements.

Returns:boolean

true if this collection contains no elements

Annotations

@Override

iterator	back to summary
public Iterator<E> iterator() Implements java.util.Collection.iterator. Iterators must be manually synchronized. synchronized (coll) { Iterator it = coll.iterator(); // do stuff with iterator } Returns:Iterator<E> an iterator that must be manually synchronized on the collection Annotations @Override

iterator

back to summary

public Iterator<E> iterator()

Implements java.util.Collection.iterator.

Iterators must be manually synchronized.

synchronized (coll) {
  Iterator it = coll.iterator();
  // do stuff with iterator
}

Returns:Iterator<E>

an iterator that must be manually synchronized on the collection

Annotations

@Override

remove back to summary

remove	back to summary
public boolean remove(final Object object) Implements java.util.Collection.remove. Doc from java.util.Collection.remove. Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element `e` such that `Objects.equals(o, e)`, if this collection contains one or more such elements. Returns `true` if this collection contained the specified element (or equivalently, if this collection changed as a result of the call). Parameters object:Object element to be removed from this collection, if present Returns:boolean `true` if an element was removed as a result of this call Annotations @Override

public boolean remove(final Object object)

Implements java.util.Collection.remove.

Doc from java.util.Collection.remove.

Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element e such that Objects.equals(o, e), if this collection contains one or more such elements. Returns true if this collection contained the specified element (or equivalently, if this collection changed as a result of the call).

Parameters

object:Object: element to be removed from this collection, if present

Returns:boolean

true if an element was removed as a result of this call

Annotations

@Override

removeAll back to summary

removeAll	back to summary
public boolean removeAll(final Collection<?> coll) Implements java.util.Collection.removeAll. Doc from java.util.Collection.removeAll. Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection. Parameters coll:Collection<?> collection containing elements to be removed from this collection Returns:boolean `true` if this collection changed as a result of the call Annotations @Override

public boolean removeAll(final Collection<?> coll)

Implements java.util.Collection.removeAll.

Doc from java.util.Collection.removeAll.

Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.

Parameters

coll:Collection<?>: collection containing elements to be removed from this collection

Returns:boolean

true if this collection changed as a result of the call

Annotations

@Override

removeIf back to summary

removeIf	back to summary
public boolean removeIf(final Predicate<? super E> filter) Overrides default java.util.Collection.removeIf. Doc from java.util.Collection.removeIf. 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. Parameters filter:Predicate<? super E> a predicate which returns `true` for elements to be removed Returns:boolean `true` if any elements were removed Annotations @Override Since 4.4

public boolean removeIf(final Predicate<? super E> filter)

Overrides default java.util.Collection.removeIf.

Doc from java.util.Collection.removeIf.

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.

Parameters

filter:Predicate<? super E>: a predicate which returns true for elements to be removed

Returns:boolean

true if any elements were removed

Annotations

@Override

Since

4.4

retainAll back to summary

retainAll	back to summary
public boolean retainAll(final Collection<?> coll) Implements java.util.Collection.retainAll. Doc from java.util.Collection.retainAll. Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection. Parameters coll:Collection<?> collection containing elements to be retained in this collection Returns:boolean `true` if this collection changed as a result of the call Annotations @Override

public boolean retainAll(final Collection<?> coll)

Implements java.util.Collection.retainAll.

Doc from java.util.Collection.retainAll.

Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.

Parameters

coll:Collection<?>: collection containing elements to be retained in this collection

Returns:boolean

true if this collection changed as a result of the call

Annotations

@Override

size back to summary

size	back to summary
public int size() Implements java.util.Collection.size. Doc from java.util.Collection.size. Returns the number of elements in this collection. If this collection contains more than `Integer.MAX_VALUE` elements, returns `Integer.MAX_VALUE`. Returns:int the number of elements in this collection Annotations @Override

public int size()

Implements java.util.Collection.size.

Doc from java.util.Collection.size.

Returns the number of elements in this collection. If this collection contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Returns:int

the number of elements in this collection

Annotations

@Override

synchronizedCollection	back to summary
public static <T> SynchronizedCollection<T> synchronizedCollection(final Collection<T> coll) Factory method to create a synchronized collection. Parameters <T> the type of the elements in the collection coll:Collection<T> the collection to decorate, must not be null Returns:SynchronizedCollection<T> a new synchronized collection Exceptions NullPointerException: if collection is null Since 4.0

synchronizedCollection

back to summary

public static <T> SynchronizedCollection<T> synchronizedCollection(final Collection<T> coll)

Factory method to create a synchronized collection.

Parameters

<T>: the type of the elements in the collection
coll:Collection<T>: the collection to decorate, must not be null

Returns:SynchronizedCollection<T>

a new synchronized collection

Exceptions

NullPointerException:: if collection is null

Since

4.0

toArray back to summary

toArray	back to summary
public Object[] toArray() Implements java.util.Collection.toArray. Doc from java.util.Collection.toArray. Returns an array containing all of the elements in this collection. If this collection 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's runtime component type is `Object`. The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array. Returns:Object[] an array, whose runtime component type is `Object`, containing all of the elements in this collection Annotations @Override

public Object[] toArray()

Implements java.util.Collection.toArray.

Doc from java.util.Collection.toArray.

Returns an array containing all of the elements in this collection. If this collection 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's runtime component type is Object.

The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.

Returns:Object[]

an array, whose runtime component type is Object, containing all of the elements in this collection

Annotations

@Override

toArray back to summary

toArray	back to summary
public <T> T[] toArray(final T[] object) Implements java.util.Collection.toArray. Doc from java.util.Collection.toArray. Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection 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 collection. If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to `null`. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any `null` elements.) If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order. Parameters <T> the component type of the array to contain the collection object:T[] the array into which the elements of this collection are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose. Returns:T[] an array containing all of the elements in this collection Annotations @Override

public <T> T[] toArray(final T[] object)

Implements java.util.Collection.toArray.

Doc from java.util.Collection.toArray.

Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection 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 collection.

If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)

If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.

Parameters

<T>: the component type of the array to contain the collection
object:T[]: the array into which the elements of this collection are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

Returns:T[]

an array containing all of the elements in this collection

Annotations

@Override

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Returns:String a string representation of the object. Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object.

Returns:String

a string representation of the object.

Annotations

@Override

public Class SynchronizedCollection<E>

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