TreeSet

A {@link NavigableSet} implementation based on a {@link TreeMap}. The elements are ordered using their {@linkplain Comparable natural ordering}, or by a {@link Comparator} provided at set creation time, depending on which constructor is used.

This implementation provides guaranteed log(n) time cost for the basic operations ({@code add}, {@code remove} and {@code contains}).

Note that the ordering maintained by a set (whether or not an explicit comparator is provided) must be consistent with equals if it is to correctly implement the {@code Set} interface. (See {@code Comparable} or {@code Comparator} for a precise definition of consistent with equals.) This is so because the {@code Set} interface is defined in terms of the {@code equals} operation, but a {@code TreeSet} instance performs all element comparisons using its {@code compareTo} (or {@code compare}) method, so two elements that are deemed equal by this method are, from the standpoint of the set, equal. The behavior of a set is well-defined even if its ordering is inconsistent with equals; it just fails to obey the general contract of the {@code Set} interface.

Note that this implementation is not synchronized. If multiple threads access a tree set concurrently, and at least one of the threads modifies the set, it must be synchronized externally. This is typically accomplished by synchronizing on some object that naturally encapsulates the set. If no such object exists, the set should be "wrapped" using the {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet} method. This is best done at creation time, to prevent accidental unsynchronized access to the set: <pre> SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre>

The iterators returned by this class's {@code iterator} method are fail-fast: if the set is modified at any time after the iterator is created, in any way except through the iterator's own {@code remove} method, the iterator will throw a {@link ConcurrentModificationException}. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw {@code ConcurrentModificationException} on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.

This class is a member of the <a href="{@docRoot}/../technotes/guides/collections/index.html"> Java Collections Framework</a>.

@param (E) the type of elements maintained by this set

@author Josh Bloch @see Collection @see Set @see HashSet @see Comparable @see Comparator @see TreeMap

Constructors

this this(NavigableMap!(E, Object) m): Constructs a set backed by the specified navigable map.
this this(): Constructs a new, empty tree set, sorted according to the natural ordering of its elements. All elements inserted into the set must implement the {@link Comparable} interface. Furthermore, all such elements must be mutually comparable: {@code e1.compareTo(e2)} must not throw a {@code ClassCastException} for any elements {@code e1} and {@code e2} in the set. If the user attempts to add an element to the set that violates this constraint (for example, the user attempts to add a string element to a set whose elements are integers), the {@code add} call will throw a {@code ClassCastException}.
this this(Comparator!E comparator): Constructs a new, empty tree set, sorted according to the specified comparator. All elements inserted into the set must be mutually comparable by the specified comparator: {@code comparator.compare(e1, e2)} must not throw a {@code ClassCastException} for any elements {@code e1} and {@code e2} in the set. If the user attempts to add an element to the set that violates this constraint, the {@code add} call will throw a {@code ClassCastException}.
this this(Collection!E c): Constructs a new tree set containing the elements in the specified collection, sorted according to the natural ordering of its elements. All elements inserted into the set must implement the {@link Comparable} interface. Furthermore, all such elements must be mutually comparable: {@code e1.compareTo(e2)} must not throw a {@code ClassCastException} for any elements {@code e1} and {@code e2} in the set.

Members

Functions

add bool add(E e): Adds the specified element to this set if it is not already present. More formally, adds the specified element {@code e} to this set if the set contains no element {@code e2} such that <tt>(e==null ? e2==null : e.equals(e2))</tt>. If this set already contains the element, the call leaves the set unchanged and returns {@code false}.
addAll bool addAll(Collection!(E) c): Adds all of the elements in the specified collection to this set.
ceiling E ceiling(E e): @throws ClassCastException {@inheritDoc} @throws NullPointerException if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
clear void clear(): Removes all of the elements from this set. The set will be empty after this call returns.
comparator Comparator!(E) comparator(): Undocumented in source. Be warned that the author may not have intended to support it.
contains bool contains(E o): Returns {@code true} if this set contains the specified element. More formally, returns {@code true} if and only if this set contains an element {@code e} such that <tt>(o==null ? e==null : o.equals(e))</tt>.
first E first(): @throws NoSuchElementException {@inheritDoc}
floor E floor(E e): @throws ClassCastException {@inheritDoc} @throws NullPointerException if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
headSet NavigableSet!(E) headSet(E toElement, bool inclusive): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code toElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
headSet SortedSet!(E) headSet(E toElement): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code toElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
higher E higher(E e): @throws ClassCastException {@inheritDoc} @throws NullPointerException if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
isEmpty bool isEmpty(): Returns {@code true} if this set contains no elements.
last E last(): @throws NoSuchElementException {@inheritDoc}
lower E lower(E e): @throws ClassCastException {@inheritDoc} @throws NullPointerException if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
opApply int opApply(int delegate(ref E) dg): Constructs a new tree set containing the same elements and using the same ordering as the specified sorted set.
opEquals bool opEquals(IObject o): Creates a <a href="Spliterator.html#binding">late-binding</a> and fail-fast {@link Spliterator} over the elements in this set.
opEquals bool opEquals(Object o): Undocumented in source. Be warned that the author may not have intended to support it.
pollFirst E pollFirst()
pollLast E pollLast()
remove bool remove(E o): Removes the specified element from this set if it is present. More formally, removes an element {@code e} such that <tt>(o==null ? e==null : o.equals(e))</tt>, if this set contains such an element. Returns {@code true} if this set contained the element (or equivalently, if this set changed as a result of the call). (This set will not contain the element once the call returns.)
size int size(): Returns the number of elements in this set (its cardinality).
subSet NavigableSet!(E) subSet(E fromElement, bool fromInclusive, E toElement, bool toInclusive): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code fromElement} or {@code toElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
subSet SortedSet!(E) subSet(E fromElement, E toElement): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code fromElement} or {@code toElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
tailSet NavigableSet!(E) tailSet(E fromElement, bool inclusive): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code fromElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
tailSet SortedSet!(E) tailSet(E fromElement): @throws ClassCastException {@inheritDoc} @throws NullPointerException if {@code fromElement} is null and this set uses natural ordering, or its comparator does not permit null elements @throws IllegalArgumentException {@inheritDoc}
toHash size_t toHash(): Undocumented in source. Be warned that the author may not have intended to support it.
toString string toString(): Undocumented in source. Be warned that the author may not have intended to support it.

TreeSet

Constructors

Members

Functions

Meta

Source