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Interfaces
- Collection<E>
- Comparator<T>
- Deque<E>
- Enumeration<E>
- EventListener
- Formattable
- Iterator<E>
- List<E>
- ListIterator<E>
- Map<K, V>
- Map.Entry<K, V>
- NavigableMap<K, V>
- NavigableSet<E>
- Observer
- Queue<E>
- RandomAccess
- Set<E>
- SortedMap<K, V>
- SortedSet<E>
Classes
- AbstractCollection<E>
- AbstractList<E>
- AbstractMap<K, V>
- AbstractMap.SimpleEntry<K, V>
- AbstractMap.SimpleImmutableEntry<K, V>
- AbstractQueue<E>
- AbstractSequentialList<E>
- AbstractSet<E>
- ArrayDeque<E>
- ArrayList<E>
- Arrays
- BitSet
- Calendar
- Collections
- Currency
- Date
- Dictionary<K, V>
- EnumMap<K extends Enum<K>, V>
- EnumSet<E extends Enum<E>>
- EventListenerProxy
- EventObject
- FormattableFlags
- Formatter
- GregorianCalendar
- HashMap<K, V>
- HashSet<E>
- Hashtable<K, V>
- IdentityHashMap<K, V>
- LinkedHashMap<K, V>
- LinkedHashSet<E>
- LinkedList<E>
- ListResourceBundle
- Locale
- Observable
- PriorityQueue<E>
- Properties
- PropertyPermission
- PropertyResourceBundle
- Random
- ResourceBundle
- ResourceBundle.Control
- Scanner
- ServiceLoader<S>
- SimpleTimeZone
- Stack<E>
- StringTokenizer
- Timer
- TimerTask
- TimeZone
- TreeMap<K, V>
- TreeSet<E>
- UUID
- Vector<E>
- WeakHashMap<K, V>
Enums
- Formatter.BigDecimalLayoutForm
Exceptions
Errors
- ServiceConfigurationError

Summary: Protected Ctors | Methods | Inherited Methods | [Expand All]

Since: API Level 1

public abstract class

AbstractCollection

extends Object
implements Collection<E>

java.lang.Object
↳	java.util.AbstractCollection<E>

Known Direct Subclasses

AbstractList<E>, AbstractQueue<E>, AbstractSet<E>, ArrayDeque<E>

Known Indirect Subclasses

AbstractSequentialList<E>, ArrayBlockingQueue<E>, ArrayList<E>, ConcurrentLinkedQueue<E>, ConcurrentSkipListSet<E>, CopyOnWriteArraySet<E>, DelayQueue<E extends Delayed>, EnumSet<E extends Enum<E>>, HashSet<E>, LinkedBlockingDeque<E>, LinkedBlockingQueue<E>, LinkedHashSet<E>, LinkedList<E>, PriorityBlockingQueue<E>, PriorityQueue<E>, Stack<E>, SynchronousQueue<E>, TreeSet<E>, Vector<E>

AbstractSequentialList<E>	AbstractSequentialList is an abstract implementation of the List interface.
ArrayBlockingQueue<E>	A bounded `blocking queue` backed by an array.
ArrayList<E>	ArrayList is an implementation of `List`, backed by an array.
ConcurrentLinkedQueue<E>	An unbounded thread-safe `queue` based on linked nodes.
ConcurrentSkipListSet<E>	A scalable concurrent `NavigableSet` implementation based on a `ConcurrentSkipListMap`.
CopyOnWriteArraySet<E>	A `Set` that uses an internal `CopyOnWriteArrayList` for all of its operations.
DelayQueue<E extends Delayed>	An unbounded `blocking queue` of `Delayed` elements, in which an element can only be taken when its delay has expired.
EnumSet<E extends Enum<E>>	An EnumSet is a specialized Set to be used with enums as keys.
HashSet<E>	HashSet is an implementation of a Set.
LinkedBlockingDeque<E>	An optionally-bounded `blocking deque` based on linked nodes.
LinkedBlockingQueue<E>	An optionally-bounded `blocking queue` based on linked nodes.
LinkedHashSet<E>	LinkedHashSet is a variant of HashSet.
LinkedList<E>	LinkedList is an implementation of `List`, backed by a doubly-linked list.
PriorityBlockingQueue<E>	An unbounded `blocking queue` that uses the same ordering rules as class `PriorityQueue` and supplies blocking retrieval operations.
PriorityQueue<E>	A PriorityQueue holds elements on a priority heap, which orders the elements according to their natural order or according to the comparator specified at construction time.
Stack<E>	`Stack` is a Last-In/First-Out(LIFO) data structure which represents a stack of objects.
SynchronousQueue<E>	A `blocking queue` in which each insert operation must wait for a corresponding remove operation by another thread, and vice versa.
TreeSet<E>	TreeSet is an implementation of SortedSet.
Vector<E>	Vector is an implementation of `List`, backed by an array and synchronized.

Class Overview

Class AbstractCollection is an abstract implementation of the Collection interface. A subclass must implement the abstract methods iterator() and size() to create an immutable collection. To create a modifiable collection it's necessary to override the add() method that currently throws an UnsupportedOperationException.

Summary

Protected Constructors
	AbstractCollection() Constructs a new instance of this AbstractCollection.

Public Methods
boolean	add(E object) Attempts to add `object` to the contents of this `Collection` (optional).
boolean	addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in `collection` to the contents of this `Collection` (optional).
void	clear() Removes all elements from this `Collection`, leaving it empty (optional).
boolean	contains(Object object) Tests whether this `Collection` contains the specified object.
boolean	containsAll(Collection<?> collection) Tests whether this `Collection` contains all objects contained in the specified `Collection`.
boolean	isEmpty() Returns if this `Collection` contains no elements.
abstract Iterator<E>	iterator() Returns an instance of `Iterator` that may be used to access the objects contained by this `Collection`.
boolean	remove(Object object) Removes one instance of the specified object from this `Collection` if one is contained (optional).
boolean	removeAll(Collection<?> collection) Removes all occurrences in this `Collection` of each object in the specified `Collection` (optional).
boolean	retainAll(Collection<?> collection) Removes all objects from this `Collection` that are not also found in the `Collection` passed (optional).
abstract int	size() Returns a count of how many objects this `Collection` contains.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this `Collection`.
Object[]	toArray() Returns a new array containing all elements contained in this `Collection`.
String	toString() Returns the string representation of this `Collection`.

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

From interface java.lang.Iterable

From interface java.util.Collection

abstract boolean	add(E object) Attempts to add `object` to the contents of this `Collection` (optional).
abstract boolean	addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in `Collection` to the contents of this `Collection` (optional).
abstract void	clear() Removes all elements from this `Collection`, leaving it empty (optional).
abstract boolean	contains(Object object) Tests whether this `Collection` contains the specified object.
abstract boolean	containsAll(Collection<?> collection) Tests whether this `Collection` contains all objects contained in the specified `Collection`.
abstract boolean	equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
abstract int	hashCode() Returns an integer hash code for the receiver.
abstract boolean	isEmpty() Returns if this `Collection` contains no elements.
abstract Iterator<E>	iterator() Returns an instance of `Iterator` that may be used to access the objects contained by this `Collection`.
abstract boolean	remove(Object object) Removes one instance of the specified object from this `Collection` if one is contained (optional).
abstract boolean	removeAll(Collection<?> collection) Removes all occurrences in this `Collection` of each object in the specified `Collection` (optional).
abstract boolean	retainAll(Collection<?> collection) Removes all objects from this `Collection` that are not also found in the `Collection` passed (optional).
abstract int	size() Returns a count of how many objects this `Collection` contains.
abstract <T> T[]	toArray(T[] array) Returns an array containing all elements contained in this `Collection`.
abstract Object[]	toArray() Returns a new array containing all elements contained in this `Collection`.

Protected Constructors

protected AbstractCollection ()

Since: API Level 1

Constructs a new instance of this AbstractCollection.

Public Methods

public boolean add (E object)

Since: API Level 1

Attempts to add object to the contents of this Collection (optional). After this method finishes successfully it is guaranteed that the object is contained in the collection. If the collection was modified it returns true, false if no changes were made. An implementation of Collection may narrow the set of accepted objects, but it has to specify this in the documentation. If the object to be added does not meet this restriction, then an IllegalArgumentException is thrown. If a collection does not yet contain an object that is to be added and adding the object fails, this method must throw an appropriate unchecked Exception. Returning false is not permitted in this case because it would violate the postcondition that the element will be part of the collection after this method finishes.

Parameters

object	the object to add.

Returns

true if this Collection is modified, false otherwise.

public boolean addAll (Collection<? extends E> collection)

Since: API Level 1

Attempts to add all of the objects contained in collection to the contents of this Collection (optional). This implementation iterates over the given Collection and calls add for each element. If any of these calls return true, then true is returned as result of this method call, false otherwise. If this Collection does not support adding elements, an UnsupportedOperationException is thrown.

If the passed Collection is changed during the process of adding elements to this Collection, the behavior depends on the behavior of the passed Collection.

Parameters

collection	the collection of objects.

Returns

true if this Collection is modified, false otherwise.

Throws

UnsupportedOperationException	if adding to this `Collection` is not supported.
ClassCastException	if the class of an object is inappropriate for this `Collection`.
IllegalArgumentException	if an object cannot be added to this `Collection`.
NullPointerException	if `collection` is `null`, or if it contains `null` elements and this `Collection` does not support such elements.

public void clear ()

Since: API Level 1

Removes all elements from this Collection, leaving it empty (optional). This implementation iterates over this Collection and calls the remove method on each element. If the iterator does not support removal of elements, an UnsupportedOperationException is thrown.

Concrete implementations usually can clear a Collection more efficiently and should therefore overwrite this method.

Throws

UnsupportedOperationException	it the iterator does not support removing elements from this `Collection`

public boolean contains (Object object)

Since: API Level 1

Tests whether this Collection contains the specified object. This implementation iterates over this Collection and tests, whether any element is equal to the given object. If object != null then object.equals(e) is called for each element e returned by the iterator until the element is found. If object == null then each element e returned by the iterator is compared with the test e == null.

Parameters

object	the object to search for.

Returns

true if object is an element of this Collection, false otherwise.

Throws

ClassCastException	if the object to look for isn't of the correct type.
NullPointerException	if the object to look for is `null` and this `Collection` doesn't support `null` elements.

public boolean containsAll (Collection<?> collection)

Since: API Level 1

Tests whether this Collection contains all objects contained in the specified Collection. This implementation iterates over the specified Collection. If one element returned by the iterator is not contained in this Collection, then false is returned; true otherwise.

Parameters

collection	the collection of objects.

Returns

true if all objects in the specified Collection are elements of this Collection, false otherwise.

Throws

ClassCastException	if one or more elements of `collection` isn't of the correct type.
NullPointerException	if `collection` contains at least one `null` element and this `Collection` doesn't support `null` elements.
NullPointerException	if `collection` is `null`.

public boolean isEmpty ()

Since: API Level 1

Returns if this Collection contains no elements. This implementation tests, whether size returns 0.

Returns

true if this Collection has no elements, false otherwise.

public abstract Iterator<E> iterator ()

Since: API Level 1

Returns an instance of Iterator that may be used to access the objects contained by this Collection. The order in which the elements are returned by the Iterator is not defined unless the instance of the Collection has a defined order. In that case, the elements are returned in that order.

In this class this method is declared abstract and has to be implemented by concrete Collection implementations.

Returns

an iterator for accessing the Collection contents.

public boolean remove (Object object)

Since: API Level 1

Removes one instance of the specified object from this Collection if one is contained (optional). This implementation iterates over this Collection and tests for each element e returned by the iterator, whether e is equal to the given object. If object != null then this test is performed using object.equals(e), otherwise using object == null. If an element equal to the given object is found, then the remove method is called on the iterator and true is returned, false otherwise. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

Parameters

object	the object to remove.

Returns

true if this Collection is modified, false otherwise.

Throws

UnsupportedOperationException	if removing from this `Collection` is not supported.
ClassCastException	if the object passed is not of the correct type.
NullPointerException	if `object` is `null` and this `Collection` doesn't support `null` elements.

public boolean removeAll (Collection<?> collection)

Since: API Level 1

Removes all occurrences in this Collection of each object in the specified Collection (optional). After this method returns none of the elements in the passed Collection can be found in this Collection anymore.

This implementation iterates over this Collection and tests for each element e returned by the iterator, whether it is contained in the specified Collection. If this test is positive, then the remove method is called on the iterator. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

Parameters

collection	the collection of objects to remove.

Returns

true if this Collection is modified, false otherwise.

Throws

UnsupportedOperationException	if removing from this `Collection` is not supported.
ClassCastException	if one or more elements of `collection` isn't of the correct type.
NullPointerException	if `collection` contains at least one `null` element and this `Collection` doesn't support `null` elements.
NullPointerException	if `collection` is `null`.

public boolean retainAll (Collection<?> collection)

Since: API Level 1

Removes all objects from this Collection that are not also found in the Collection passed (optional). After this method returns this Collection will only contain elements that also can be found in the Collection passed to this method.

This implementation iterates over this Collection and tests for each element e returned by the iterator, whether it is contained in the specified Collection. If this test is negative, then the remove method is called on the iterator. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

Parameters

collection	the collection of objects to retain.

Returns

true if this Collection is modified, false otherwise.

Throws

UnsupportedOperationException	if removing from this `Collection` is not supported.
ClassCastException	if one or more elements of `collection` isn't of the correct type.
NullPointerException	if `collection` contains at least one `null` element and this `Collection` doesn't support `null` elements.
NullPointerException	if `collection` is `null`.

public abstract int size ()

Since: API Level 1

Returns a count of how many objects this Collection contains.

In this class this method is declared abstract and has to be implemented by concrete Collection implementations.

Returns

how many objects this Collection contains, or Integer.MAX_VALUE if there are more than Integer.MAX_VALUE elements in this Collection.

public T[] toArray (T[] contents)

Since: API Level 1

Returns an array containing all elements contained in this Collection. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this Collection, the array element following the Collection elements is set to null. If the implementation has ordered elements it will return the element array in the same order as an iterator would return them. toArray(new Object[0]) behaves exactly the same way as toArray() does.

Parameters

contents	the array.

Returns

an array of the elements from this Collection.

public Object[] toArray ()

Since: API Level 1

Returns a new array containing all elements contained in this Collection. If the implementation has ordered elements it will return the element array in the same order as an iterator would return them. The array returned does not reflect any changes of the Collection. A new array is created even if the underlying data structure is already an array.

Returns

an array of the elements from this Collection.

public String toString ()

Since: API Level 1

Returns the string representation of this Collection. The presentation has a specific format. It is enclosed by square brackets ("[]"). Elements are separated by ', ' (comma and space).

Returns

the string representation of this Collection.

Results

Interfaces

Classes

Enums

Exceptions

Errors

AbstractCollection

Class Overview

Summary

Protected Constructors

protected AbstractCollection ()

Public Methods

public boolean add (E object)

Parameters

Returns

public boolean addAll (Collection<? extends E> collection)

Parameters

Returns

Throws

public void clear ()

Throws

See Also

public boolean contains (Object object)

Parameters

Returns

Throws

public boolean containsAll (Collection<?> collection)

Parameters

Returns

Throws

public boolean isEmpty ()

Returns

See Also

public abstract Iterator<E> iterator ()

Returns

public boolean remove (Object object)

Parameters

Returns

Throws

public boolean removeAll (Collection<?> collection)

Parameters

Returns

Throws

public boolean retainAll (Collection<?> collection)

Parameters

Returns

Throws

public abstract int size ()

Returns

public T[] toArray (T[] contents)

Parameters

Returns

public Object[] toArray ()

Returns

public String toString ()

Returns