Class IndexedTreeSet<E>
- Type Parameters:
E
- the type of elements maintained by this set
- All Implemented Interfaces:
IndexedNavigableSet<E>
,Serializable
,Cloneable
,Iterable<E>
,Collection<E>
,NavigableSet<E>
,Set<E>
,SortedSet<E>
NavigableSet
implementation based on a IndexedTreeMap
.
The elements are ordered using their natural
ordering, 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 IndexedTreeSet
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
method. This is best done at creation time, to prevent accidental
unsynchronized access to the set:
SortedSet s = Collections.synchronizedSortedSet(new IndexedTreeSet(...));
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.
- Since:
- 1.2
- See Also:
-
Constructor Summary
ConstructorsConstructorDescriptionConstructs a new, empty tree set, sorted according to the natural ordering of its elements.IndexedTreeSet
(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.IndexedTreeSet
(Comparator<? super E> comparator) Constructs a new, empty tree set, sorted according to the specified comparator.IndexedTreeSet
(SortedSet<E> s) Constructs a new tree set containing the same elements and using the same ordering as the specified sorted set. -
Method Summary
Modifier and TypeMethodDescriptionboolean
Adds the specified element to this set if it is not already present.boolean
addAll
(Collection<? extends E> c) Adds all of the elements in the specified collection to this set.void
clear()
Removes all of the elements from this set.Comparator<? super E>
boolean
Returnstrue
if this set contains the specified element.void
debug()
Returns an iterator over the elements in this set in descending order.int
entryIndex
(E e) Searches the specified tree map for the specified entry using the put algorithm.exact
(int index) Returns the entry located at the index offset from the beginning of the sorted setfirst()
boolean
isEmpty()
Returnstrue
if this set contains no elements.iterator()
Returns an iterator over the elements in this set in ascending order.last()
pollLast()
boolean
Removes the specified element from this set if it is present.int
size()
Returns the number of elements in this set (its cardinality).Methods inherited from class java.util.AbstractSet
equals, hashCode, removeAll
Methods inherited from class java.util.AbstractCollection
containsAll, retainAll, toArray, toArray, toString
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray
Methods inherited from interface java.util.Set
containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray
Methods inherited from interface java.util.SortedSet
spliterator
-
Constructor Details
-
IndexedTreeSet
public IndexedTreeSet()Constructs a new, empty tree set, sorted according to the natural ordering of its elements. All elements inserted into the set must implement theComparable
interface. Furthermore, all such elements must be mutually comparable:e1.compareTo(e2)
must not throw aClassCastException
for any elementse1
ande2
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), theadd
call will throw aClassCastException
. -
IndexedTreeSet
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 aClassCastException
for any elementse1
ande2
in the set. If the user attempts to add an element to the set that violates this constraint, theadd
call will throw aClassCastException
.- Parameters:
comparator
- the comparator that will be used to order this set. Ifnull
, the natural ordering of the elements will be used.
-
IndexedTreeSet
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 theComparable
interface. Furthermore, all such elements must be mutually comparable:e1.compareTo(e2)
must not throw aClassCastException
for any elementse1
ande2
in the set.- Parameters:
c
- collection whose elements will comprise the new set- Throws:
ClassCastException
- if the elements inc
are notComparable
, or are not mutually comparableNullPointerException
- if the specified collection is null
-
IndexedTreeSet
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
-
-
Method Details
-
iterator
Returns an iterator over the elements in this set in ascending order.- Specified by:
iterator
in interfaceCollection<E>
- Specified by:
iterator
in interfaceIterable<E>
- Specified by:
iterator
in interfaceNavigableSet<E>
- Specified by:
iterator
in interfaceSet<E>
- Specified by:
iterator
in classAbstractCollection<E>
- Returns:
- an iterator over the elements in this set in ascending order
-
descendingIterator
Returns an iterator over the elements in this set in descending order.- Specified by:
descendingIterator
in interfaceNavigableSet<E>
- Returns:
- an iterator over the elements in this set in descending order
- Since:
- 1.6
-
descendingSet
- Specified by:
descendingSet
in interfaceNavigableSet<E>
- Since:
- 1.6
-
size
public int size()Returns the number of elements in this set (its cardinality).- Specified by:
size
in interfaceCollection<E>
- Specified by:
size
in interfaceSet<E>
- Specified by:
size
in classAbstractCollection<E>
- Returns:
- the number of elements in this set (its cardinality)
-
isEmpty
public boolean isEmpty()Returnstrue
if this set contains no elements.- Specified by:
isEmpty
in interfaceCollection<E>
- Specified by:
isEmpty
in interfaceSet<E>
- Overrides:
isEmpty
in classAbstractCollection<E>
- Returns:
true
if this set contains no elements
-
contains
Returnstrue
if this set contains the specified element. More formally, returnstrue
if and only if this set contains an elemente
such that (o==null ? e==null : o.equals(e)).- Specified by:
contains
in interfaceCollection<E>
- Specified by:
contains
in interfaceSet<E>
- Overrides:
contains
in classAbstractCollection<E>
- Parameters:
o
- object to be checked for containment in this set- Returns:
true
if this set contains the specified element- Throws:
ClassCastException
- if the specified object cannot be compared with the elements currently in the setNullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
-
add
Adds the specified element to this set if it is not already present. More formally, adds the specified elemente
to this set if the set contains no elemente2
such that (e==null ? e2==null : e.equals(e2)). If this set already contains the element, the call leaves the set unchanged and returnsfalse
.- Specified by:
add
in interfaceCollection<E>
- Specified by:
add
in interfaceSet<E>
- Overrides:
add
in classAbstractCollection<E>
- Parameters:
e
- element to be added to this set- Returns:
true
if this set did not already contain the specified element- Throws:
ClassCastException
- if the specified object cannot be compared with the elements currently in this setNullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
-
remove
Removes the specified element from this set if it is present. More formally, removes an elemente
such that (o==null ? e==null : o.equals(e)), if this set contains such an element. Returnstrue
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.)- Specified by:
remove
in interfaceCollection<E>
- Specified by:
remove
in interfaceSet<E>
- Overrides:
remove
in classAbstractCollection<E>
- Parameters:
o
- object to be removed from this set, if present- Returns:
true
if this set con tained the specified element- Throws:
ClassCastException
- if the specified object cannot be compared with the elements currently in this setNullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
-
clear
public void clear()Removes all of the elements from this set. The set will be empty after this call returns.- Specified by:
clear
in interfaceCollection<E>
- Specified by:
clear
in interfaceSet<E>
- Overrides:
clear
in classAbstractCollection<E>
-
addAll
Adds all of the elements in the specified collection to this set.- Specified by:
addAll
in interfaceCollection<E>
- Specified by:
addAll
in interfaceSet<E>
- Overrides:
addAll
in classAbstractCollection<E>
- Parameters:
c
- collection containing elements to be added to this set- Returns:
true
if this set changed as a result of the call- Throws:
ClassCastException
- if the elements provided cannot be compared with the elements currently in the setNullPointerException
- if the specified collection is null or if any element is null and this set uses natural ordering, or its comparator does not permit null elements
-
subSet
public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) - Specified by:
subSet
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- iffromElement
ortoElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
- Since:
- 1.6
-
headSet
- Specified by:
headSet
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- iftoElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
- Since:
- 1.6
-
tailSet
- Specified by:
tailSet
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- iffromElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
- Since:
- 1.6
-
subSet
- Specified by:
subSet
in interfaceNavigableSet<E>
- Specified by:
subSet
in interfaceSortedSet<E>
- Throws:
ClassCastException
NullPointerException
- iffromElement
ortoElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
-
headSet
- Specified by:
headSet
in interfaceNavigableSet<E>
- Specified by:
headSet
in interfaceSortedSet<E>
- Throws:
ClassCastException
NullPointerException
- iftoElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
-
tailSet
- Specified by:
tailSet
in interfaceNavigableSet<E>
- Specified by:
tailSet
in interfaceSortedSet<E>
- Throws:
ClassCastException
NullPointerException
- iffromElement
is null and this set uses natural ordering, or its comparator does not permit null elementsIllegalArgumentException
-
comparator
- Specified by:
comparator
in interfaceSortedSet<E>
-
first
- Specified by:
first
in interfaceSortedSet<E>
- Throws:
NoSuchElementException
-
last
- Specified by:
last
in interfaceSortedSet<E>
- Throws:
NoSuchElementException
-
lower
- Specified by:
lower
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements- Since:
- 1.6
-
floor
- Specified by:
floor
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements- Since:
- 1.6
-
ceiling
- Specified by:
ceiling
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements- Since:
- 1.6
-
higher
- Specified by:
higher
in interfaceNavigableSet<E>
- Throws:
ClassCastException
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements- Since:
- 1.6
-
pollFirst
- Specified by:
pollFirst
in interfaceNavigableSet<E>
- Since:
- 1.6
-
pollLast
- Specified by:
pollLast
in interfaceNavigableSet<E>
- Since:
- 1.6
-
exact
Description copied from interface:IndexedNavigableSet
Returns the entry located at the index offset from the beginning of the sorted set- Specified by:
exact
in interfaceIndexedNavigableSet<E>
- Parameters:
index
- index of the entry- Returns:
- the entry located at the index (@code index) offset from the beginning of the sorted set
-
entryIndex
Description copied from interface:IndexedNavigableSet
Searches the specified tree map for the specified entry using the put algorithm. Calculates its offset from the beginning of the sorted map using weights.- Specified by:
entryIndex
in interfaceIndexedNavigableSet<E>
- Parameters:
e
- the entry- Returns:
- index of the searched entry, if it is contained in the tree map; otherwise a NullPointerException is thrown
-
debug
- Throws:
Exception
-