public interface Set<E>

ExtendsCollection<E>, Iterable<E>

Known subtypesComponentSelector, AbstractSet, HashSet, LinkedHashSet, NavigableSet, SortedSet, TreeSet

A Set is a data structure which does not allow duplicate elements.

Methods

public abstract boolean add(E object)Adds the specified object to this set.
public abstract boolean addAll(Collection<? extends E> collection)Adds the objects in the specified collection which do not exist yet in this set.
public abstract void clear()Removes all elements from this set, leaving it empty.
public abstract boolean contains(Object object)Searches this set for the specified object.
public abstract boolean containsAll(Collection<?> collection)Searches this set for all objects in the specified collection.
public abstract boolean equals(Object object)Compares the specified object to this set, and returns true if they represent the same object using a class specific comparison.
public abstract int hashCode()Returns the hash code for this set.
public abstract boolean isEmpty()Returns true if this set has no elements.
public abstract Iterator<E> iterator()Returns an iterator on the elements of this set.
public abstract boolean remove(Object object)Removes the specified object from this set.
public abstract boolean removeAll(Collection<?> collection)Removes all objects in the specified collection from this set.
public abstract boolean retainAll(Collection<?> collection)Removes all objects from this set that are not contained in the specified collection.
public abstract int size()Returns the number of elements in this set.
public abstract Object[] toArray()Returns an array containing all elements contained in this set.
public abstract <T> T[] toArray(T[] array)Returns an array containing all elements contained in this set.

Inherited methods

From Collection

removeIf

From Iterable

forEach

Method details

add

public abstract boolean add(E object)
Adds the specified object to this set. The set is not modified if it already contains the object.

Parameters

object E
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 abstract boolean addAll(Collection<? extends E> collection)
Adds the objects in the specified collection which do not exist yet in this set.

Parameters

collection Collection<? extends E>
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 abstract void clear()
Removes all elements from this set, leaving it empty.

Throws

UnsupportedOperationException
when removing from this set is not supported.

See also

contains

public abstract boolean contains(Object object)
Searches this set for the specified object.

Parameters

object Object
the object to search for.

Returns

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

containsAll

public abstract boolean containsAll(Collection<?> collection)
Searches this set for all objects in the specified collection.

Parameters

collection Collection<?>
the collection of objects.

Returns

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

equals

public abstract boolean equals(Object object)
Compares the specified object to this set, and returns true if they represent the same object using a class specific comparison. Equality for a set means that both sets have the same size and the same elements.

Parameters

object Object
the object to compare with this object.

Returns

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

See also

hashCode

public abstract int hashCode()
Returns the hash code for this set. Two set which are equal must return the same value.

Returns

the hash code of this set.

See also

isEmpty

public abstract boolean isEmpty()
Returns true if this set has no elements.

Returns

true if this set has no elements, false otherwise.

See also

iterator

public abstract Iterator<E> iterator()
Returns an iterator on the elements of this set. The elements are unordered.

Returns

an iterator on the elements of this set.

See also

remove

public abstract boolean remove(Object object)
Removes the specified object from this set.

Parameters

object Object
the object to remove.

Returns

true if this set was modified, false otherwise.

Throws

UnsupportedOperationException
when removing from this set is not supported.

removeAll

public abstract boolean removeAll(Collection<?> collection)
Removes all objects in the specified collection from this set.

Parameters

collection Collection<?>
the collection of objects to remove.

Returns

true if this set was modified, false otherwise.

Throws

UnsupportedOperationException
when removing from this set is not supported.

retainAll

public abstract boolean retainAll(Collection<?> collection)
Removes all objects from this set that are not contained in the specified collection.

Parameters

collection Collection<?>
the collection of objects to retain.

Returns

true if this set was modified, false otherwise.

Throws

UnsupportedOperationException
when removing from this set is not supported.

size

public abstract int size()
Returns the number of elements in this set.

Returns

the number of elements in this set.

toArray

public abstract Object[] toArray()
Returns an array containing all elements contained in this set.

Returns

an array of the elements from this set.

toArray

public abstract <T> T[] toArray(T[] array)
Returns 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.

Parameters

array T[]
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.

See also