E - the type of elements maintained by this setpublic interface NavigableSet<E> extends SortedSet<E>
SortedSet extended with navigation methods reporting
closest matches for given search targets. Methods lower,
floor, ceiling, and higher return elements
respectively less than, less than or equal, greater than or equal,
and greater than a given element, returning null if there
is no such element. A NavigableSet may be accessed and
traversed in either ascending or descending order. The descendingSet method returns a view of the set with the senses of
all relational and directional methods inverted. The performance of
ascending operations and views is likely to be faster than that of
descending ones. This interface additionally defines methods
pollFirst and pollLast that return and remove the
lowest and highest element, if one exists, else returning null. Methods subSet, headSet,
and tailSet differ from the like-named SortedSet methods in accepting additional arguments describing
whether lower and upper bounds are inclusive versus exclusive.
Subsets of any NavigableSet must implement the NavigableSet interface.
The return values of navigation methods may be ambiguous in
implementations that permit null elements. However, even
in this case the result can be disambiguated by checking
contains(null). To avoid such issues, implementations of
this interface are encouraged to not permit insertion of
null elements. (Note that sorted sets of Comparable elements intrinsically do not permit null.)
Methods
subSet(E, E),
headSet(E), and
tailSet(E)
are specified to return SortedSet to allow existing
implementations of SortedSet to be compatibly retrofitted to
implement NavigableSet, but extensions and implementations
of this interface are encouraged to override these methods to return
NavigableSet.
This interface is a member of the Java Collections Framework.
| Modifier and Type | Method and Description |
|---|---|
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. |
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 |
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 toElement)
Returns a view of the portion of this set whose elements are
strictly less than toElement.
|
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. |
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. |
Iterator<E> |
iterator()
Returns an iterator over the elements in this set, in ascending order.
|
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. |
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. |
SortedSet<E> |
subSet(E fromElement,
E toElement)
Returns a view of the portion of this set whose elements range
from fromElement, inclusive, to toElement,
exclusive.
|
SortedSet<E> |
tailSet(E fromElement)
Returns a view of the portion of this set whose elements are
greater than or equal to fromElement.
|
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. |
comparator, first, lastE lower(E e)
null if there is no such element.e - the value to matche,
or null if there is no such elementClassCastException - if the specified element cannot be
compared with the elements currently in the setNullPointerException - if the specified element is null
and this set does not permit null elementsE floor(E e)
null if there is no such element.e - the value to matche,
or null if there is no such elementClassCastException - if the specified element cannot be
compared with the elements currently in the setNullPointerException - if the specified element is null
and this set does not permit null elementsE ceiling(E e)
null if there is no such element.e - the value to matche,
or null if there is no such elementClassCastException - if the specified element cannot be
compared with the elements currently in the setNullPointerException - if the specified element is null
and this set does not permit null elementsE higher(E e)
null if there is no such element.e - the value to matche,
or null if there is no such elementClassCastException - if the specified element cannot be
compared with the elements currently in the setNullPointerException - if the specified element is null
and this set does not permit null elementsE pollFirst()
null if this set is empty.null if this set is emptyE pollLast()
null if this set is empty.null if this set is emptyIterator<E> iterator()
NavigableSet<E> descendingSet()
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.
Iterator<E> descendingIterator()
descendingSet().iterator().NavigableSet<E> subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
fromElement to toElement. If fromElement and
toElement are equal, the returned set is empty unless fromInclusive and toInclusive 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.
fromElement - low endpoint of the returned setfromInclusive - true if the low endpoint
is to be included in the returned viewtoElement - high endpoint of the returned settoInclusive - true if the high endpoint
is to be included in the returned viewfromElement, inclusive, to toElement, exclusiveClassCastException - 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 does
not permit null elementsIllegalArgumentException - 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.NavigableSet<E> headSet(E toElement, boolean inclusive)
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.
toElement - high endpoint of the returned setinclusive - true if the high endpoint
is to be included in the returned viewinclusive is true) toElementClassCastException - 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 does not permit null elementsIllegalArgumentException - if this set itself has a
restricted range, and toElement lies outside the
bounds of the rangeNavigableSet<E> tailSet(E fromElement, boolean inclusive)
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.
fromElement - low endpoint of the returned setinclusive - true if the low endpoint
is to be included in the returned viewfromElementClassCastException - 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 does not permit null elementsIllegalArgumentException - if this set itself has a
restricted range, and fromElement lies outside the
bounds of the rangeSortedSet<E> subSet(E fromElement, E toElement)
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to subSet(fromElement, true, toElement, false).
subSet in interface SortedSet<E>fromElement - low endpoint (inclusive) of the returned settoElement - high endpoint (exclusive) of the returned setClassCastException - 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 does not permit null
elementsIllegalArgumentException - 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 rangeSortedSet<E> headSet(E toElement)
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to headSet(toElement, false).
headSet in interface SortedSet<E>toElement - high endpoint (exclusive) of the returned setClassCastException - 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 does not permit null elementsIllegalArgumentException - if this set itself has a
restricted range, and toElement lies outside the
bounds of the range
naSortedSet<E> tailSet(E fromElement)
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to tailSet(fromElement, true).
tailSet in interface SortedSet<E>fromElement - low endpoint (inclusive) of the returned setClassCastException - 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 does not permit null elementsIllegalArgumentException - if this set itself has a
restricted range, and fromElement lies outside the
bounds of the range Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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