public interface

Set

implements Collection<E>
java.util.Set<E>
Known Indirect Subclasses

Class Overview

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

Summary

Public Methods
abstract boolean add(E object)
Adds the specified object to this set.
abstract boolean addAll(Collection<? extends E> collection)
Adds the objects in the specified collection which do not exist yet in this set.
abstract void clear()
Removes all elements from this set, leaving it empty.
abstract boolean contains(Object object)
Searches this set for the specified object.
abstract boolean containsAll(Collection<?> collection)
Searches this set for all objects in the specified collection.
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.
abstract int hashCode()
Returns the hash code for this set.
abstract boolean isEmpty()
Returns true if this set has no elements.
abstract Iterator<E> iterator()
Returns an iterator on the elements of this set.
abstract boolean remove(Object object)
Removes the specified object from this set.
abstract boolean removeAll(Collection<?> collection)
Removes all objects in the specified collection from this set.
abstract boolean retainAll(Collection<?> collection)
Removes all objects from this set that are not contained in the specified collection.
abstract int size()
Returns the number of elements in this set.
abstract <T> T[] toArray(T[] array)
Returns an array containing all elements contained in this set.
abstract Object[] toArray()
Returns an array containing all elements contained in this set.
[Expand]
Inherited Methods
From interface java.lang.Iterable
From interface java.util.Collection

Public Methods

public abstract boolean add (E object)

Since: API Level 1

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

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.

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

Since: API Level 1

Adds the objects in the specified collection which do not exist yet in this set.

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.

public abstract void clear ()

Since: API Level 1

Removes all elements from this set, leaving it empty.

Throws
UnsupportedOperationException when removing from this set is not supported.
See Also

public abstract boolean contains (Object object)

Since: API Level 1

Searches this set for the specified object.

Parameters
object the object to search for.
Returns
  • true if object is an element of this set, false otherwise.

public abstract boolean containsAll (Collection<?> collection)

Since: API Level 1

Searches this set for all objects in the specified collection.

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

public abstract boolean equals (Object object)

Since: API Level 1

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 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

public abstract int hashCode ()

Since: API Level 1

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

public abstract boolean isEmpty ()

Since: API Level 1

Returns true if this set has no elements.

Returns
  • true if this set has no elements, false otherwise.
See Also

public abstract Iterator<E> iterator ()

Since: API Level 1

Returns an iterator on the elements of this set. The elements are unordered.

Returns
  • an iterator on the elements of this set.
See Also

public abstract boolean remove (Object object)

Since: API Level 1

Removes the specified object from this set.

Parameters
object the object to remove.
Returns
  • true if this set was modified, false otherwise.
Throws
UnsupportedOperationException when removing from this set is not supported.

public abstract boolean removeAll (Collection<?> collection)

Since: API Level 1

Removes all objects in the specified collection from this set.

Parameters
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.

public abstract boolean retainAll (Collection<?> collection)

Since: API Level 1

Removes all objects from this set that are not contained in the specified collection.

Parameters
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.

public abstract int size ()

Since: API Level 1

Returns the number of elements in this set.

Returns
  • the number of elements in this set.

public abstract T[] toArray (T[] array)

Since: API Level 1

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 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

public abstract Object[] toArray ()

Since: API Level 1

Returns an array containing all elements contained in this set.

Returns
  • an array of the elements from this set.