java.util
Interface Set

All Superinterfaces:

Collection, Iterable

All Known Implementing Classes:

AbstractSet, HashSet

public interface Set

extends Collection

Set is a collection which does not allow duplicate elements.

Since:

1.2

Method Summary

boolean	add(java.lang.Object object) Adds the specified object to this Set.
boolean	addAll(Collection collection) Adds the objects in the specified Collection which do not exist in this Set.
void	clear() Removes all elements from this Set, leaving it empty.
boolean	contains(java.lang.Object object) Searches this Set for the specified object.
boolean	containsAll(Collection collection) Searches this Set for all objects in the specified Collection.
boolean	equals(java.lang.Object object) Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
int	hashCode() Answers an integer hash code for the receiver.
boolean	isEmpty() Answers if this Set has no elements, a size of zero.
Iterator	iterator() Answers an Iterator on the elements of this Set.
boolean	remove(java.lang.Object object) Removes any occurrence of the specified object from this Set.
boolean	removeAll(Collection collection) Removes all objects in the specified Collection from this Set.
boolean	retainAll(Collection collection) Removes all objects from this Set that are not contained in the specified Collection.
int	size() Answers the number of elements in this Set.
java.lang.Object[]	toArray() Answers an array containing all elements contained in this Set.
java.lang.Object[]	toArray(java.lang.Object[] array) Answers an array containing all elements contained in this Set.

Method Detail

add

public boolean add(java.lang.Object object)

Adds the specified object to this Set. The Set is not modified if it already contains the object.

Specified by:

add in interface Collection

Parameters:

object - the object to add

Returns:

true if this Set is modified, false otherwise

Throws:

UnsupportedOperationException - when adding to this Set is not supported

ClassCastException - when the class of the object is inappropriate for this Set

IllegalArgumentException - when the object cannot be added to this Set

addAll

public boolean addAll(Collection collection)

Adds the objects in the specified Collection which do not exist in this Set.

Specified by:

addAll in interface Collection

Parameters:

collection - the Collection of objects

Returns:

true if this Set is modified, false otherwise

Throws:

UnsupportedOperationException - when adding to this Set is not supported

ClassCastException - when the class of an object is inappropriate for this Set

IllegalArgumentException - when an object cannot be added to this Set

clear

public void clear()

Removes all elements from this Set, leaving it empty.

Specified by:

clear in interface Collection

Throws:

UnsupportedOperationException - when removing from this Set is not supported

See Also:

isEmpty(), size()

contains

public boolean contains(java.lang.Object object)

Searches this Set for the specified object.

Specified by:

contains in interface Collection

Parameters:

object - the object to search for

Returns:

true if object is an element of this Set, false otherwise

containsAll

public boolean containsAll(Collection collection)

Searches this Set for all objects in the specified Collection.

Specified by:

containsAll in interface Collection

Parameters:

collection - the Collection of objects

Returns:

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

equals

public boolean equals(java.lang.Object object)

Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.

Specified by:

equals in interface Collection

Parameters:

object - Object the object to compare with this object.

Returns:

boolean true if the object is the same as this object false if it is different from this object.

See Also:

hashCode()

hashCode

public int hashCode()

Answers an integer hash code for the receiver. Objects which are equal answer the same value for this method.

Specified by:

hashCode in interface Collection

Returns:

the receiver's hash

See Also:

equals(java.lang.Object)

isEmpty

public boolean isEmpty()

Answers if this Set has no elements, a size of zero.

Specified by:

isEmpty in interface Collection

Returns:

true if this Set has no elements, false otherwise

See Also:

size()

iterator

public Iterator iterator()

Answers an Iterator on the elements of this Set.

Specified by:

iterator in interface Collection

Returns:

an Iterator on the elements of this Set

See Also:

Iterator

remove

public boolean remove(java.lang.Object object)

Removes any occurrence of the specified object from this Set.

Specified by:

remove in interface Collection

Parameters:

object - the object to remove

Returns:

true if this Set is modified, false otherwise

Throws:

UnsupportedOperationException - when removing from this Set is not supported

removeAll

public boolean removeAll(Collection collection)

Removes all objects in the specified Collection from this Set.

Specified by:

removeAll in interface Collection

Parameters:

collection - the Collection of objects to remove

Returns:

true if this Set is modified, false otherwise

Throws:

UnsupportedOperationException - when removing from this Set is not supported

retainAll

public boolean retainAll(Collection collection)

Removes all objects from this Set that are not contained in the specified Collection.

Specified by:

retainAll in interface Collection

Parameters:

collection - the Collection of objects to retain

Returns:

true if this Set is modified, false otherwise

Throws:

UnsupportedOperationException - when removing from this Set is not supported

size

public int size()

Answers the number of elements in this Set.

Specified by:

size in interface Collection

Returns:

the number of elements in this Set

toArray

public java.lang.Object[] toArray()

Answers an array containing all elements contained in this Set.

Specified by:

toArray in interface Collection

Returns:

an array of the elements from this Set

toArray

public java.lang.Object[] toArray(java.lang.Object[] array)

Answers an array containing all elements contained in this Set. 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 Set, the array element following the collection elements is set to null.

Specified by:

toArray in interface Collection

Parameters:

array - the array

Returns:

an array of the elements from this Set

Throws:

ArrayStoreException - when the type of an element in this Set cannot be stored in the type of the specified array