Class AbstractSet<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, Set<E>

Direct Known Subclasses:

HashSet, TreeSet

public abstract class AbstractSet<E>
extends AbstractCollection<E>
implements Set<E>

An AbstractSet is an abstract implementation of the Set interface. This implementation does not support adding. A subclass must implement the abstract methods iterator() and size().

Since:

1.2

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractSet()	Constructs a new instance of this AbstractSet.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object object)	Compares the specified object to this Set and returns true if they are equal.
int	hashCode()	Returns the hash code for this set.
boolean	removeAll(Collection<?> collection)	Removes all occurrences in this collection which are contained in the specified collection.

Methods inherited from class AbstractCollection

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, size, toArray, toArray, toString

Modifier and Type	Method	Description
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	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.
Object[]	toArray()	Returns a new array containing all elements contained in this ArrayList.
<T> T[]	toArray(T[] contents)	Returns an array containing all elements contained in this ArrayList.
String	toString()	Returns the string representation of this Collection.

Methods inherited from class Object

clone, getClass, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()
final Class	getClass()	Returns the runtime class of an object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
final void	wait()	Causes current thread to wait until another thread invokes the method or the method for this object.
final void	wait(long timeout)	Causes current thread to wait until either another thread invokes the method or the method for this object, or a specified amount of time has elapsed.
final void	wait(long timeout, int nanos)	Causes current thread to wait until another thread invokes the method or the method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.

Methods inherited from interface Set

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, retainAll, size, toArray, toArray

Modifier and Type	Method	Description
boolean	add(E object)	Adds the specified object to this set.
boolean	addAll(Collection<? extends E> collection)	Adds the objects in the specified collection which do not exist yet in this set.
void	clear()	Removes all elements from this set, leaving it empty.
boolean	contains(Object object)	Searches this set for the specified object.
boolean	containsAll(Collection<?> collection)	Searches this set for all objects in the specified collection.
boolean	isEmpty()	Returns true if this set has no elements.
Iterator<E>	iterator()	Returns an iterator on the elements of this set.
boolean	remove(Object object)	Removes the specified object from this set.
boolean	retainAll(Collection<?> collection)	Removes all objects from this set that are not contained in the specified collection.
int	size()	Returns the number of elements in this set.
Object[]	toArray()	Returns an array containing all elements contained in this set.
<T> T[]	toArray(T[] array)	Returns an array containing all elements contained in this set.

Constructor Details

AbstractSet

protected AbstractSet()

Constructs a new instance of this AbstractSet.

Method Details

equals

public boolean equals(Object object)

Compares the specified object to this Set and returns true if they are equal. The object must be an instance of Set and contain the same objects.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface Set<E>

Overrides:

equals in class Object

Parameters:

object - the object to compare with this set.

Returns:

true if the specified object is equal to this set, false otherwise

See Also:

• hashCode()

hashCode

public int hashCode()

Returns the hash code for this set. Two set which are equal must return the same value. This implementation calculates the hash code by adding each element's hash code.

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface Set<E>

Overrides:

hashCode in class Object

Returns:

the hash code of this set.

See Also:

• equals(Object)

removeAll

public boolean removeAll(Collection<?> collection)

Removes all occurrences in this collection which are contained in the specified collection.

Specified by:

removeAll in interface Collection<E>

Specified by:

removeAll in interface Set<E>

Overrides:

removeAll in class AbstractCollection<E>

Parameters:

collection - the collection of objects to remove.

Returns:

true if this collection was modified, false otherwise.

Throws:

UnsupportedOperationException - if removing from this collection is not supported.