| java.util.TreeSet
| TreeSet | | public class TreeSet extends AbstractSet implements NavigableSet<E>,Cloneable,java.io.Serializable(Code) | | A
NavigableSet implementation based on a
TreeMap .
The elements are ordered using their
, or by a
Comparator provided at set creation
time, depending on which constructor is used.
This implementation provides guaranteed log(n) time cost for the basic
operations (
add ,
remove and
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
Set interface. (See
Comparable or
Comparator for a precise definition of consistent with
equals.) This is so because the
Set interface is defined in
terms of the
equals operation, but a
TreeSet instance
performs all element comparisons using its
compareTo (or
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
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
Collections.synchronizedSortedSet Collections.synchronizedSortedSet method. This is best done at creation time, to prevent accidental
unsynchronized access to the set:
SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));
The iterators returned by this class's
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
remove method, the iterator will throw a
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
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
Java Collections Framework.
<
Parameters:
E - > the type of elements maintained by this set
author:
Josh Bloch
version:
1.43, 05/05/07
See Also: Collection
See Also: Set
See Also: HashSet
See Also: Comparable
See Also: Comparator
See Also: TreeMap
since:
1.2 |
| Constructor Summary | |
| | TreeSet(NavigableMap<E, Object> m)
Constructs a set backed by the specified navigable map. | | public | TreeSet()
Constructs a new, empty tree set, sorted according to the
natural ordering of its elements. | | public | TreeSet(Comparator<? super E> comparator)
Constructs a new, empty tree set, sorted according to the specified
comparator. | | public | TreeSet(Collection<? extends E> c)
Constructs a new tree set containing the elements in the specified
collection, sorted according to the natural ordering of its
elements. | | public | TreeSet(SortedSet<E> s)
Constructs a new tree set containing the same elements and
using the same ordering as the specified sorted set. |
| Method Summary | |
| public boolean | add(E e)
Adds the specified element to this set if it is not already present. | | public boolean | addAll(Collection<? extends E> c)
Adds all of the elements in the specified collection to this set. | | public E | ceiling(E e)
| | public void | clear()
Removes all of the elements from this set. | | public Object | clone()
Returns a shallow copy of this
TreeSet instance. | | public Comparator<? super E> | comparator()
| | public boolean | contains(Object o)
Returns
true if this set contains the specified element. | | public Iterator<E> | descendingIterator()
Returns an iterator over the elements in this set in descending order. | | public NavigableSet<E> | descendingSet()
| | public E | first()
| | public E | floor(E e)
| | public NavigableSet<E> | headSet(E toElement, boolean inclusive)
| | public SortedSet<E> | headSet(E toElement)
| | public E | higher(E e)
| | public boolean | isEmpty()
Returns
true if this set contains no elements. | | public Iterator<E> | iterator()
Returns an iterator over the elements in this set in ascending order. | | public E | last()
| | public E | lower(E e)
| | public E | pollFirst()
| | public E | pollLast()
| | public boolean | remove(Object o)
Removes the specified element from this set if it is present.
More formally, removes an element
e such that
(o==null ? e==null : o.equals(e)),
if this set contains such an element. | | public int | size()
Returns the number of elements in this set (its cardinality). | | public NavigableSet<E> | subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
| | public SortedSet<E> | subSet(E fromElement, E toElement)
| | public NavigableSet<E> | tailSet(E fromElement, boolean inclusive)
| | public SortedSet<E> | tailSet(E fromElement)
|
| TreeSet | | public TreeSet()(Code) | | Constructs a new, empty tree set, sorted according to the
natural ordering of its elements. All elements inserted into
the set must implement the
Comparable interface.
Furthermore, all such elements must be mutually
comparable:
e1.compareTo(e2) must not throw a
ClassCastException for any elements
e1 and
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
add call will throw a
ClassCastException .
|
| TreeSet | | public TreeSet(Comparator<? super E> comparator)(Code) | | 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:
comparator.compare(e1, e2) must not throw a
ClassCastException for any elements
e1 and
e2 in the set. If the user attempts to add
an element to the set that violates this constraint, the
add call will throw a
ClassCastException .
Parameters:
comparator - the comparator that will be used to order this set.If null , the of the elements will be used. |
| TreeSet | | public TreeSet(Collection<? extends E> c)(Code) | | 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
Comparable interface. Furthermore, all such elements must be
mutually comparable:
e1.compareTo(e2) must not throw a
ClassCastException for any elements
e1 and
e2 in the set.
Parameters:
c - collection whose elements will comprise the new set
throws:
ClassCastException - if the elements in c arenot Comparable, or are not mutually comparable
throws:
NullPointerException - if the specified collection is null |
| TreeSet | | public TreeSet(SortedSet<E> s)(Code) | | Constructs a new tree set containing the same elements and
using the same ordering as the specified sorted set.
Parameters:
s - sorted set whose elements will comprise the new set
throws:
NullPointerException - if the specified sorted set is null |
| add | | public boolean add(E e)(Code) | | Adds the specified element to this set if it is not already present.
More formally, adds the specified element
e to this set if
the set contains no element
e2 such that
(e==null ? e2==null : e.equals(e2)).
If this set already contains the element, the call leaves the set
unchanged and returns
false .
Parameters:
e - element to be added to this set true if this set did not already contain the specifiedelement
throws:
ClassCastException - if the specified object cannot be comparedwith the elements currently in this set
throws:
NullPointerException - if the specified element is nulland this set uses natural ordering, or its comparatordoes not permit null elements |
| addAll | | public boolean addAll(Collection<? extends E> c)(Code) | | Adds all of the elements in the specified collection to this set.
Parameters:
c - collection containing elements to be added to this set true if this set changed as a result of the call
throws:
ClassCastException - if the elements provided cannot be comparedwith the elements currently in the set
throws:
NullPointerException - if the specified collection is null orif any element is null and this set uses natural ordering, orits comparator does not permit null elements |
| clear | | public void clear()(Code) | | Removes all of the elements from this set.
The set will be empty after this call returns.
|
| clone | | public Object clone()(Code) | | Returns a shallow copy of this
TreeSet instance. (The elements
themselves are not cloned.)
a shallow copy of this set |
| contains | | public boolean contains(Object o)(Code) | | Returns
true if this set contains the specified element.
More formally, returns
true if and only if this set
contains an element
e such that
(o==null ? e==null : o.equals(e)).
Parameters:
o - object to be checked for containment in this set true if this set contains the specified element
throws:
ClassCastException - if the specified object cannot be comparedwith the elements currently in the set
throws:
NullPointerException - if the specified element is nulland this set uses natural ordering, or its comparatordoes not permit null elements |
| descendingIterator | | public Iterator<E> descendingIterator()(Code) | | Returns an iterator over the elements in this set in descending order.
an iterator over the elements in this set in descending order
since:
1.6 |
| isEmpty | | public boolean isEmpty()(Code) | | Returns
true if this set contains no elements.
true if this set contains no elements |
| iterator | | public Iterator<E> iterator()(Code) | | Returns an iterator over the elements in this set in ascending order.
an iterator over the elements in this set in ascending order |
| pollFirst | | public E pollFirst()(Code) | |
since:
1.6 |
| pollLast | | public E pollLast()(Code) | |
since:
1.6 |
| remove | | public boolean remove(Object o)(Code) | | Removes the specified element from this set if it is present.
More formally, removes an element
e such that
(o==null ? e==null : o.equals(e)),
if this set contains such an element. Returns
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.)
Parameters:
o - object to be removed from this set, if present true if this set contained the specified element
throws:
ClassCastException - if the specified object cannot be comparedwith the elements currently in this set
throws:
NullPointerException - if the specified element is nulland this set uses natural ordering, or its comparatordoes not permit null elements |
| size | | public int size()(Code) | | Returns the number of elements in this set (its cardinality).
the number of elements in this set (its cardinality) |
|
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