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

Since: API Level 1

public class

TreeSet

extends AbstractSet<E>
implements Serializable Cloneable NavigableSet<E>

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

Class Overview

TreeSet is an implementation of SortedSet. All optional operations (adding and removing) are supported. The elements can be any objects which are comparable to each other either using their natural order or a specified Comparator.

Summary

Public Constructors
	TreeSet() Constructs a new empty instance of `TreeSet` which uses natural ordering.
	TreeSet(Collection<? extends E> collection) Constructs a new instance of `TreeSet` which uses natural ordering and containing the unique elements in the specified collection.
	TreeSet(Comparator<? super E> comparator) Constructs a new empty instance of `TreeSet` which uses the specified comparator.
	TreeSet(SortedSet<E> set) Constructs a new instance of `TreeSet` containing the elements of the specified SortedSet and using the same Comparator.

Public Methods
boolean	add(E object) Adds the specified object to this `TreeSet`.
boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified collection to this `TreeSet`.
E	ceiling(E e) Returns the least element in this set greater than or equal to the given element, or `null` if there is no such element.
void	clear() Removes all elements from this `TreeSet`, leaving it empty.
Object	clone() Returns a new `TreeSet` with the same elements, size and comparator as this `TreeSet`.
Comparator<? super E>	comparator() Returns the comparator used to compare elements in this `TreeSet`.
boolean	contains(Object object) Searches this `TreeSet` for the specified object.
Iterator<E>	descendingIterator() Returns an iterator over the elements in this set, in descending order.
NavigableSet<E>	descendingSet() Returns a reverse order view of the elements contained in this set.
E	first() Returns the first element in this set.
E	floor(E e) Returns the greatest element in this set less than or equal to the given element, or `null` if there is no such element.
SortedSet<E>	headSet(E end) Returns a `SortedSet` of the specified portion of this `TreeSet` which contains elements less than the end element.
NavigableSet<E>	headSet(E end, boolean endInclusive) Returns a view of the portion of this set whose elements are less than (or equal to, if `inclusive` is true) `toElement`.
E	higher(E e) Returns the least element in this set strictly greater than the given element, or `null` if there is no such element.
boolean	isEmpty() Returns true if this `TreeSet` has no element, otherwise false.
Iterator<E>	iterator() Returns an Iterator on the elements of this `TreeSet`.
E	last() Returns the last element in this set.
E	lower(E e) Returns the greatest element in this set strictly less than the given element, or `null` if there is no such element.
E	pollFirst() Retrieves and removes the first (lowest) element, or returns `null` if this set is empty.
E	pollLast() Retrieves and removes the last (highest) element, or returns `null` if this set is empty.
boolean	remove(Object object) Removes an occurrence of the specified object from this `TreeSet`.
int	size() Returns the number of elements in this `TreeSet`.
SortedSet<E>	subSet(E start, E end) Returns a `SortedSet` of the specified portion of this `TreeSet` which contains elements greater or equal to the start element but less than the end element.
NavigableSet<E>	subSet(E start, boolean startInclusive, E end, boolean endInclusive) Returns a view of the portion of this set whose elements range from `fromElement` to `toElement`.
NavigableSet<E>	tailSet(E start, boolean startInclusive) Returns a view of the portion of this set whose elements are greater than (or equal to, if `inclusive` is true) `fromElement`.
SortedSet<E>	tailSet(E start) Returns a `SortedSet` of the specified portion of this `TreeSet` which contains elements greater or equal to the start element.

[Expand]

Inherited Methods

From class java.util.AbstractSet

From class java.util.AbstractCollection

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`.

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`.

From interface java.util.NavigableSet

abstract E	ceiling(E e) Returns the least element in this set greater than or equal to the given element, or `null` if there is no such element.
abstract Iterator<E>	descendingIterator() Returns an iterator over the elements in this set, in descending order.
abstract NavigableSet<E>	descendingSet() Returns a reverse order view of the elements contained in this set.
abstract E	floor(E e) Returns the greatest element in this set less than or equal to the given element, or `null` if there is no such element.
abstract SortedSet<E>	headSet(E toElement) Returns a `SortedSet` of the specified portion of this `SortedSet` which contains elements less than the end element. Equivalent to `headSet(toElement, false)`.
abstract NavigableSet<E>	headSet(E toElement, boolean inclusive) Returns a view of the portion of this set whose elements are less than (or equal to, if `inclusive` is true) `toElement`.
abstract E	higher(E e) Returns the least element in this set strictly greater than the given element, or `null` if there is no such element.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this set, in ascending order.
abstract E	lower(E e) Returns the greatest element in this set strictly less than the given element, or `null` if there is no such element.
abstract E	pollFirst() Retrieves and removes the first (lowest) element, or returns `null` if this set is empty.
abstract E	pollLast() Retrieves and removes the last (highest) element, or returns `null` if this set is empty.
abstract SortedSet<E>	subSet(E fromElement, E toElement) Returns a `SortedSet` of the specified portion of this `SortedSet` which contains elements greater or equal to the start element but less than the end element. Equivalent to `subSet(fromElement, true, toElement, false)`.
abstract NavigableSet<E>	subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) Returns a view of the portion of this set whose elements range from `fromElement` to `toElement`.
abstract NavigableSet<E>	tailSet(E fromElement, boolean inclusive) Returns a view of the portion of this set whose elements are greater than (or equal to, if `inclusive` is true) `fromElement`.
abstract SortedSet<E>	tailSet(E fromElement) Returns a `SortedSet` of the specified portion of this `SortedSet` which contains elements greater or equal to the start element. Equivalent to `tailSet(fromElement, true)`.

From interface java.util.Set

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.

From interface java.util.SortedSet

Public Constructors

public TreeSet ()

Since: API Level 1

Constructs a new empty instance of TreeSet which uses natural ordering.

public TreeSet (Collection<? extends E> collection)

Since: API Level 1

Constructs a new instance of TreeSet which uses natural ordering and containing the unique elements in the specified collection.

Parameters

collection	the collection of elements to add.

Throws

ClassCastException	when an element in the collection does not implement the Comparable interface, or the elements in the collection cannot be compared.

public TreeSet (Comparator<? super E> comparator)

Since: API Level 1

Constructs a new empty instance of TreeSet which uses the specified comparator.

Parameters

comparator	the comparator to use.

public TreeSet (SortedSet<E> set)

Since: API Level 1

Constructs a new instance of TreeSet containing the elements of the specified SortedSet and using the same Comparator.

Parameters

set	the SortedSet of elements to add.

Public Methods

public boolean add (E object)

Since: API Level 1

Adds the specified object to this TreeSet.

Parameters

object	the object to add.

Returns

true when this TreeSet did not already contain the object, false otherwise.

Throws

ClassCastException	when the object cannot be compared with the elements in this `TreeSet`.
NullPointerException	when the object is null and the comparator cannot handle null.

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

Since: API Level 1

Adds the objects in the specified collection to this TreeSet.

Parameters

collection	the collection of objects to add.

Returns

true if this TreeSet was modified, false otherwise.

Throws

ClassCastException	when an object in the collection cannot be compared with the elements in this `TreeSet`.
NullPointerException	when an object in the collection is null and the comparator cannot handle null.

public E ceiling (E e)

Since: API Level 9

Returns the least element in this set greater than or equal to the given element, or null if there is no such element.

Parameters

e	the value to match

Returns

the least element greater than or equal to e, or null if there is no such element

public void clear ()

Since: API Level 1

Removes all elements from this TreeSet, leaving it empty.

public Object clone ()

Since: API Level 1

Returns a new TreeSet with the same elements, size and comparator as this TreeSet.

Returns

a shallow copy of this TreeSet.

public Comparator<? super E> comparator ()

Since: API Level 1

Returns the comparator used to compare elements in this TreeSet.

Returns

a Comparator or null if the natural ordering is used

public boolean contains (Object object)

Since: API Level 1

Searches this TreeSet for the specified object.

Parameters

object	the object to search for.

Returns

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

Throws

ClassCastException	when the object cannot be compared with the elements in this `TreeSet`.
NullPointerException	when the object is null and the comparator cannot handle null.

public Iterator<E> descendingIterator ()

Since: API Level 9

Returns an iterator over the elements in this set, in descending order. Equivalent in effect to descendingSet().iterator().

Returns

an iterator over the elements in this set, in descending order

public NavigableSet<E> descendingSet ()

Since: API Level 9

Returns a reverse order view of the elements contained in this set. The descending set is backed by this set, so changes to the set are reflected in the descending set, and vice-versa. If either set is modified while an iteration over either set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined.

The returned set has an ordering equivalent to Collections.reverseOrder(comparator()). The expression s.descendingSet().descendingSet() returns a view of s essentially equivalent to s.

Returns

a reverse order view of this set

public E first ()

Since: API Level 1

Returns the first element in this set.

Returns

the first element.

Throws

NoSuchElementException	when this TreeSet is empty

public E floor (E e)

Since: API Level 9

Returns the greatest element in this set less than or equal to the given element, or null if there is no such element.

Parameters

e	the value to match

Returns

the greatest element less than or equal to e, or null if there is no such element

public SortedSet<E> headSet (E end)

Since: API Level 1

Returns a SortedSet of the specified portion of this TreeSet which contains elements less than the end element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.

Parameters

end	the end element

Returns

a subset where the elements are less than end

Throws

ClassCastException	when the end object cannot be compared with the elements in this TreeSet
NullPointerException	when the end object is null and the comparator cannot handle null

public NavigableSet<E> headSet (E end, boolean endInclusive)

Since: API Level 9

Returns a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.

The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.

Parameters

end	high endpoint of the returned set
endInclusive	`true` if the high endpoint is to be included in the returned view

Returns

a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement

public E higher (E e)

Since: API Level 9

Returns the least element in this set strictly greater than the given element, or null if there is no such element.

Parameters

e	the value to match

Returns

the least element greater than e, or null if there is no such element

public boolean isEmpty ()

Since: API Level 1

Returns true if this TreeSet has no element, otherwise false.

Returns

true if this TreeSet has no element.

public Iterator<E> iterator ()

Since: API Level 1

Returns an Iterator on the elements of this TreeSet.

Returns

an Iterator on the elements of this TreeSet.

public E last ()

Since: API Level 1

Returns the last element in this set.

Returns

the last element.

Throws

NoSuchElementException	when this TreeSet is empty

public E lower (E e)

Since: API Level 9

Returns the greatest element in this set strictly less than the given element, or null if there is no such element.

Parameters

e	the value to match

Returns

the greatest element less than e, or null if there is no such element

public E pollFirst ()

Since: API Level 9

Retrieves and removes the first (lowest) element, or returns null if this set is empty.

Returns

the first element, or null if this set is empty

public E pollLast ()

Since: API Level 9

Retrieves and removes the last (highest) element, or returns null if this set is empty.

Returns

the last element, or null if this set is empty

public boolean remove (Object object)

Since: API Level 1

Removes an occurrence of the specified object from this TreeSet.

Parameters

object	the object to remove.

Returns

true if this TreeSet was modified, false otherwise.

Throws

ClassCastException	when the object cannot be compared with the elements in this `TreeSet`.
NullPointerException	when the object is null and the comparator cannot handle null.

public int size ()

Since: API Level 1

Returns the number of elements in this TreeSet.

Returns

the number of elements in this TreeSet.

public SortedSet<E> subSet (E start, E end)

Since: API Level 1

Returns a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element but less than the end element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.

Parameters

start	the start element
end	the end element

Returns

a subset where the elements are greater or equal to start and less than end

Throws

ClassCastException	when the start or end object cannot be compared with the elements in this TreeSet
NullPointerException	when the start or end object is null and the comparator cannot handle null

public NavigableSet<E> subSet (E start, boolean startInclusive, E end, boolean endInclusive)

Since: API Level 9

Returns a view of the portion of this set whose elements range from fromElement to toElement. If fromElement and toElement are equal, the returned set is empty unless fromExclusive and toExclusive are both true. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.

The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.

Parameters

start	low endpoint of the returned set
startInclusive	`true` if the low endpoint is to be included in the returned view
end	high endpoint of the returned set
endInclusive	`true` if the high endpoint is to be included in the returned view

Returns

a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive

public NavigableSet<E> tailSet (E start, boolean startInclusive)

Since: API Level 9

Returns a view of the portion of this set whose elements are greater than (or equal to, if inclusive is true) fromElement. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.

The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.

Parameters

start	low endpoint of the returned set
startInclusive	`true` if the low endpoint is to be included in the returned view

Returns

a view of the portion of this set whose elements are greater than or equal to fromElement

public SortedSet<E> tailSet (E start)

Since: API Level 1

Returns a SortedSet of the specified portion of this TreeSet which contains elements greater or equal to the start element. The returned SortedSet is backed by this TreeSet so changes to one are reflected by the other.

Parameters

start	the start element

Returns

a subset where the elements are greater or equal to start

Throws

ClassCastException	when the start object cannot be compared with the elements in this TreeSet
NullPointerException	when the start object is null and the comparator cannot handle null

Results

Interfaces

Classes

Enums

Exceptions

Errors

TreeSet

Class Overview

Summary

Public Constructors

public TreeSet ()

public TreeSet (Collection<? extends E> collection)

Parameters

Throws

public TreeSet (Comparator<? super E> comparator)

Parameters

public TreeSet (SortedSet<E> set)

Parameters

Public Methods

public boolean add (E object)

Parameters

Returns

Throws

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

Parameters

Returns

Throws

public E ceiling (E e)

Parameters

Returns

See Also

public void clear ()

See Also

public Object clone ()

Returns

See Also

public Comparator<? super E> comparator ()

Returns

public boolean contains (Object object)

Parameters

Returns

Throws

public Iterator<E> descendingIterator ()

Returns

See Also

public NavigableSet<E> descendingSet ()

Returns

See Also

public E first ()

Returns

Throws

public E floor (E e)

Parameters

Returns

See Also

public SortedSet<E> headSet (E end)

Parameters

Returns

Throws

public NavigableSet<E> headSet (E end, boolean endInclusive)

Parameters

Returns

See Also

public E higher (E e)

Parameters

Returns

See Also

public boolean isEmpty ()

Returns

See Also

public Iterator<E> iterator ()

Returns

See Also

public E last ()

Returns

Throws

public E lower (E e)

Parameters

Returns

See Also