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java.util
Class TreeSet<E>
java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractSet<E>
java.util.TreeSet<E>
-
-
Type Parameters:
-
E - the type of elements maintained by this set
-
All Implemented Interfaces:
-
Serializable
,
Cloneable
,
Iterable
<E>,
Collection
<E>,
NavigableSet
<E>,
Set
<E>,
SortedSet
<E>
-
public class TreeSet<E>
- extends AbstractSet<E>
- implements NavigableSet<E>, Cloneable, Serializable
A
NavigableSet
implementation based on a
TreeMap
. 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,
(
add
,
remove
and
contains).
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)
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 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
Java Collections Framework
.
-
Since:
-
1.2
-
See Also:
-
Collection
,
Set
,
HashSet
,
Comparable
,
Comparator
,
TreeMap
,
Serialized Form
Constructor Summary
|
TreeSet
()
Constructs a new, empty tree set, sorted according to the natural ordering of its elements. |
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. |
TreeSet
(
Comparator
<? super
E
> comparator)
Constructs a new, empty tree set, sorted according to the specified comparator. |
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
|
boolean |
add
(
E
e)
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. |
E
|
ceiling
(
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 of the elements from this set. |
Object
|
clone
()
Returns a shallow copy of this
TreeSet
instance. |
Comparator
<? super
E
> |
comparator
()
Returns the comparator used to order the elements in this set, or
null
if this set uses the
natural ordering
of its elements. |
boolean |
contains
(
Object
Returns
true
if this set contains the specified element. |
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 (lowest) element currently in this set. |
E
|
floor
(
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
Returns a view of the portion of this set whose elements are strictly less than
Equivalent to
navigableHeadSet(E)
toElement
SortedSet
.
interface.
|
NavigableSet
<
E
|
headSet
higher
(
E
Returns
a view of
the
portion of
least element in
this set
whose elements are less
strictly greater
than
(or equal to,
the given element, or
null
if
inclusive
there
is
true) toElement.
no such element.
|
E
|
higher
(
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 set contains no elements.
|
boolean
|
isEmpty
()
Returns true if this set contains no elements.
|
Iterator
<
E
> |
iterator
()
Returns an iterator over the elements in this set in ascending order. |
E
|
last
()
Returns the last (highest) element currently in this set. |
E
|
lower
(
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.
|
NavigableSet
<
E
|
navigableHeadSet
(
E
Returns a view of the portion of this set whose elements are strictly less than
toElement
.
|
E
|
pollLast
()
Retrieves and removes the last (highest) element, or returns null if this set is empty.
|
NavigableSet
<
E
|
navigableSubSet
(
E
fromElement,
E
Returns a view of the portion of this set whose elements range from
fromElement
, inclusive, to
toElement
, exclusive.
|
NavigableSet
<
E
|
navigableTailSet
(
E
Returns a view of the portion of this set whose elements are greater than or equal to
fromElement
.
|
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
o)
Removes the specified element from this set if it is present. |
int |
size
()
Returns the number of elements in this set (its cardinality). |
NavigableSet
SortedSet
<
E
|
subSet
subSet
(
E
fromElement,
boolean fromInclusive,
E
Returns a view of the portion of this set whose elements range from fromElement
Equivalent
to
toElement.
navigableSubSet(E, E)
SortedSet
interface.
|
SortedSet
<
E
|
subSet
tailSet
(
E
fromElement,
E
Returns a view of the portion of this set whose elements range from
fromElement
, inclusive,
Equivalent
to
navigableTailSet(E)
toElement
SortedSet
, exclusive.
interface.
|
SortedSet
<
E
|
tailSet
(
E
Returns a view of the portion of this set whose elements are greater than or equal to
fromElement
.
|
NavigableSet
<
E
|
tailSet
(
E
Returns a view of the portion of this set whose elements are greater than (or equal to, if inclusive is true) fromElement.
|
TreeSet
public TreeSet()
-
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
add(Object)
call will throw a
ClassCastException.
ClassCastException
.
TreeSet
public TreeSet(Comparator<? super 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:
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
add(Object)
call will throw a
ClassCastException.
ClassCastException
.
-
Parameters:
-
comparator - the comparator that will be used to order this set. If
null,
null
,
the
natural ordering
of the elements will be used.
TreeSet
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. 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
are not
Comparable
, or are not mutually comparable
-
NullPointerException
- if the specified collection is null
TreeSet
public TreeSet(SortedSet<E> s)
-
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
iterator
public Iterator<E> iterator()
-
Returns an iterator over the elements in this set in ascending order.
-
-
Specified by:
-
iterator
in interface
Iterable
<
E
>
-
Specified by:
-
iterator
in interface
Collection
<
E
>
-
Specified by:
-
iterator
in interface
NavigableSet
<
E
>
-
Specified by:
-
iterator
in interface
Set
<
E
>
-
Specified by:
-
iterator
in class
AbstractCollection
<
E
>
-
-
Returns:
-
an iterator over the elements in this set in ascending order
descendingIterator
public Iterator<E> descendingIterator()
-
Returns an iterator over the elements in this set in descending order.
-
-
Specified by:
-
descendingIterator
in interface
NavigableSet
<
E
>
-
-
Returns:
-
an iterator over the elements in this set in descending order
-
Since:
-
1.6
descendingSet
public
NavigableSet
<
E
>
descendingSet
()
-
Description copied from interface:
NavigableSet
-
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.
-
-
Specified by:
-
descendingSet
in interface
NavigableSet
<
E
>
-
-
Returns:
-
a reverse order view of this set
-
Since:
-
1.6
size
public int size()
-
Returns the number of elements in this set (its cardinality).
-
-
Specified by:
-
size
in interface
Collection
<
E
>
-
Specified by:
-
size
in interface
Set
<
E
>
-
Specified by:
-
size
in class
AbstractCollection
<
E
>
-
-
Returns:
-
the number of elements in this set (its cardinality)
isEmpty
public boolean isEmpty()
-
Returns
true
if this set contains no elements.
-
-
Specified by:
-
isEmpty
in interface
Collection
<
E
>
-
Specified by:
-
isEmpty
in interface
Set
<
E
>
-
Overrides:
-
isEmpty
in class
AbstractCollection
<
E
>
-
-
Returns:
-
true
if this set contains no elements
contains
public boolean contains(Object o)
-
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
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))
.
-
-
Specified by:
-
contains
in interface
Collection
<
E
>
-
Specified by:
-
contains
in interface
Set
<
E
>
-
Overrides:
-
contains
in class
AbstractCollection
<
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 set
-
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
add
public boolean add(E e)
-
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
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.
false
.
-
-
Specified by:
-
add
in interface
Collection
<
E
>
-
Specified by:
-
add
in interface
Set
<
E
>
-
Overrides:
-
add
in class
AbstractCollection
<
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 set
-
NullPointerException
- if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements
remove
public boolean remove(Object o)
-
Removes the specified element from this set if it is present. More formally, removes an element
e such that
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.)
-
-
Specified by:
-
remove
in interface
Collection
<
E
>
-
Specified by:
-
remove
in interface
Set
<
E
>
-
Overrides:
-
remove
in class
AbstractCollection
<
E
>
-
-
Parameters:
-
o - object to be removed from this set, if present
-
Returns:
-
true
if this set contained the specified element
-
Throws:
-
ClassCastException
- if the specified object cannot be compared with the elements currently in this set
-
NullPointerException
- 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 interface
Collection
<
E
>
-
Specified by:
-
clear
in interface
Set
<
E
>
-
Overrides:
-
clear
in class
AbstractCollection
<
E
>
-
addAll
public boolean addAll(Collection<? extends E> c)
-
Adds all of the elements in the specified collection to this set.
-
-
Specified by:
-
addAll
in interface
Collection
<
E
>
-
Specified by:
-
addAll
in interface
Set
<
E
>
-
Overrides:
-
addAll
in class
AbstractCollection
<
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 set
-
NullPointerException
- 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
-
See Also:
-
AbstractCollection.add(Object)
subSet
navigableSubSet
public NavigableSet<E>
subSet ![](../../diffpics/oold.gif)
navigableSubSet (E fromElement,
boolean fromInclusive,
E
toElement,
boolean toInclusive) ![](../../diffpics/oold.gif)
toElement)
-
Description copied from interface:
NavigableSet
NavigableSet
-
Returns a view of the portion of this set whose elements range from
fromElement
, inclusive,
to
toElement. If
toElement
, exclusive. (If
fromElement
and
toElement
are equal, the returned set is
empty unless fromExclusive and toExclusive are both true.
empty.)
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.
-
-
Specified by:
-
subSet
navigableSubSet
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
fromElement - low endpoint
(inclusive)
of the returned set -
fromInclusive - true if the low endpoint is to be included in the returned view
-
toElement - high endpoint of the returned set
-
toInclusive - true if the high endpoint is to be included in the returned view
toElement - high endpoint (exclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements range from
fromElement,
fromElement
,
inclusive, to
toElement,
toElement
,
exclusive -
Throws:
-
ClassCastException
- if
fromElement
and
toElement
cannot be compared to one another using this set's comparator (or, if the set has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if
fromElement
or
toElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
fromElement
or
toElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if
fromElement
is greater than
toElement;
toElement
;
or if this set itself has a restricted range, and
fromElement
or
toElement
lies outside the bounds of the range. -
Since:
-
1.6
headSet
navigableHeadSet
public NavigableSet<E>
headSet ![](../../diffpics/oold.gif)
navigableHeadSet (E
toElement,
boolean inclusive) ![](../../diffpics/oold.gif)
toElement)
-
Description copied from interface:
NavigableSet
NavigableSet
-
Returns a view of the portion of this set whose elements are
strictly
less than
(or equal to, if inclusive is true) toElement.
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.
-
-
Specified by:
-
headSet
navigableHeadSet
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
toElement - high endpoint of the returned set
-
inclusive - true if the high endpoint is to be included in the returned view
toElement - high endpoint (exclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements are
strictly
less than
(or equal to, if inclusive is true)
toElement
-
Throws:
-
ClassCastException
- if
toElement
is not compatible with this set's comparator (or, if the set has no comparator, if
toElement
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
toElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
toElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if this set itself has a restricted range, and
toElement
lies outside the bounds of the range
-
Since:
-
1.6
tailSet
navigableTailSet
public NavigableSet<E>
tailSet ![](../../diffpics/oold.gif)
navigableTailSet (E
fromElement,
boolean inclusive) ![](../../diffpics/oold.gif)
fromElement)
-
Description copied from interface:
NavigableSet
NavigableSet
-
Returns a view of the portion of this set whose elements are greater than
(or
or
equal
to, if inclusive is true) fromElement.
to
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.
-
-
Specified by:
-
tailSet
navigableTailSet
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
fromElement - low endpoint of the returned set
-
inclusive - true if the low endpoint is to be included in the returned view
fromElement - low endpoint (inclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements are greater than or equal to
fromElement
-
Throws:
-
ClassCastException
- if
fromElement
is not compatible with this set's comparator (or, if the set has no comparator, if
fromElement
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
fromElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
fromElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if this set itself has a restricted range, and
fromElement
lies outside the bounds of the range
-
Since:
-
1.6
subSet
public SortedSet<E> subSet(E fromElement,
E toElement)
-
Description copied from interface:
NavigableSet
Equivalent to
navigableSubSet(E, E)
-
but with a return type conforming to the
SortedSet
interface.
Returns a view of the portion of this set whose elements range from
fromElement
, inclusive, to
toElement
, exclusive. (If
fromElement
and
toElement
are equal, the returned set is empty.) 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.
Equivalent to subSet(fromElement, true, toElement, false).
-
-
Specified by:
-
subSet
in interface
NavigableSet
<
E
>
-
Specified by:
-
subSet
in interface
SortedSet
<
E
>
-
-
Parameters:
-
fromElement - low endpoint (inclusive) of the returned set
-
toElement - high endpoint (exclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements range from
fromElement
, inclusive, to
toElement
, exclusive
-
Throws:
-
ClassCastException
- if
fromElement
and
toElement
cannot be compared to one another using this set's comparator (or, if the set has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if
fromElement
or
toElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
fromElement
or
toElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if
fromElement
is greater than
toElement
; or if this set itself has a restricted range, and
fromElement
or
toElement
lies outside the bounds of the range
headSet
public SortedSet<E> headSet(E toElement)
-
Description copied from interface:
NavigableSet
Equivalent to
navigableHeadSet(E)
-
but with a return type conforming to the
SortedSet
interface.
Returns a view of the portion of this set whose elements are strictly less than
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.
Equivalent to headSet(toElement, false).
-
-
Specified by:
-
headSet
in interface
NavigableSet
<
E
>
-
Specified by:
-
headSet
in interface
SortedSet
<
E
>
-
-
Parameters:
-
toElement - high endpoint (exclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements are strictly less than
toElement
-
Throws:
-
ClassCastException
- if
toElement
is not compatible with this set's comparator (or, if the set has no comparator, if
toElement
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
toElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
toElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if this set itself has a restricted range, and
toElement
lies outside the bounds of the
rangena
range
tailSet
public SortedSet<E> tailSet(E fromElement)
-
Description copied from interface:
NavigableSet
Equivalent to
navigableTailSet(E)
-
but with a return type conforming to the
SortedSet
interface.
Returns a view of the portion of this set whose elements are greater than or equal to
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.
Equivalent to tailSet(fromElement, true).
-
-
Specified by:
-
tailSet
in interface
NavigableSet
<
E
>
-
Specified by:
-
tailSet
in interface
SortedSet
<
E
>
-
-
Parameters:
-
fromElement - low endpoint (inclusive) of the returned set
-
Returns:
-
a view of the portion of this set whose elements are greater than or equal to
fromElement
-
Throws:
-
ClassCastException
- if
fromElement
is not compatible with this set's comparator (or, if the set has no comparator, if
fromElement
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
fromElement
cannot be compared to elements currently in the set.
-
NullPointerException
- if
fromElement
is null and this set uses natural ordering, or its comparator does not permit null elements
-
IllegalArgumentException
- if this set itself has a restricted range, and
fromElement
lies outside the bounds of the range
comparator
public Comparator<? super E> comparator()
-
Description copied from interface:
SortedSet
-
Returns the comparator used to order the elements in this set, or
null
if this set uses the
natural ordering
of its elements.
-
-
Specified by:
-
comparator
in interface
SortedSet
<
E
>
-
-
Returns:
-
the comparator used to order the elements in this set, or
null
if this set uses the natural ordering of its elements
first
public E first()
-
Description copied from interface:
SortedSet
-
Returns the first (lowest) element currently in this set.
-
-
Specified by:
-
first
in interface
SortedSet
<
E
>
-
-
Returns:
-
the first (lowest) element currently in this set
-
Throws:
-
NoSuchElementException
- if this set is empty
last
public E last()
-
Description copied from interface:
SortedSet
-
Returns the last (highest) element currently in this set.
-
-
Specified by:
-
last
in interface
SortedSet
<
E
>
-
-
Returns:
-
the last (highest) element currently in this set
-
Throws:
-
NoSuchElementException
- if this set is empty
lower
public E lower(E e)
-
Description copied from interface:
NavigableSet
-
Returns the greatest element in this set strictly less than the given element, or
null
if there is no such element.
-
-
Specified by:
-
lower
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
e - the value to match
-
Returns:
-
the greatest element less than
e,
e
,
or
null
if there is no such element -
Throws:
-
ClassCastException
- if the specified element cannot be compared with the elements currently in the set
-
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
public E floor(E e)
-
Description copied from interface:
NavigableSet
-
Returns the greatest element in this set less than or equal to the given element, or
null
if there is no such element.
-
-
Specified by:
-
floor
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
e - the value to match
-
Returns:
-
the greatest element less than or equal to
e,
e
,
or
null
if there is no such element -
Throws:
-
ClassCastException
- if the specified element cannot be compared with the elements currently in the set
-
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
public E ceiling(E e)
-
Description copied from interface:
NavigableSet
-
Returns the least element in this set greater than or equal to the given element, or
null
if there is no such element.
-
-
Specified by:
-
ceiling
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
e - the value to match
-
Returns:
-
the least element greater than or equal to
e,
e
,
or
null
if there is no such element -
Throws:
-
ClassCastException
- if the specified element cannot be compared with the elements currently in the set
-
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
public E higher(E e)
-
Description copied from interface:
NavigableSet
-
Returns the least element in this set strictly greater than the given element, or
null
if there is no such element.
-
-
Specified by:
-
higher
in interface
NavigableSet
<
E
>
-
-
Parameters:
-
e - the value to match
-
Returns:
-
the least element greater than
e,
e
,
or
null
if there is no such element -
Throws:
-
ClassCastException
- if the specified element cannot be compared with the elements currently in the set
-
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
public E pollFirst()
-
Description copied from interface:
NavigableSet
-
Retrieves and removes the first (lowest) element, or returns
null
if this set is empty.
-
-
Specified by:
-
pollFirst
in interface
NavigableSet
<
E
>
-
-
Returns:
-
the first element, or
null
if this set is empty
-
Since:
-
1.6
pollLast
public E pollLast()
-
Description copied from interface:
NavigableSet
-
Retrieves and removes the last (highest) element, or returns
null
if this set is empty.
-
-
Specified by:
-
pollLast
in interface
NavigableSet
<
E
>
-
-
Returns:
-
the last element, or
null
if this set is empty
-
Since:
-
1.6
clone
public Object clone()
-
Returns a shallow copy of this
TreeSet
instance. (The elements themselves are not cloned.)
-
-
Overrides:
-
clone
in class
Object
-
-
Returns:
-
a shallow copy of this set
-
See Also:
-
Cloneable