Skip to content

Most visited

Recently visited

navigation
Added in API level 9

NavigableSet

public interface NavigableSet
implements SortedSet<E>

java.util.NavigableSet<E>
Known Indirect Subclasses


A 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.

Summary

Public methods

abstract 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.

abstract Iterator<E> descendingIterator()

Returns an iterator over the elements in this set, in descending order.

abstract NavigableSet<E> descendingSet()

Returns a reverse order view of the elements contained in this set.

abstract 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.

abstract SortedSet<E> headSet(E toElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements less than the end element.

Equivalent to headSet(toElement, false).

abstract 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.

abstract 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.

abstract Iterator<E> iterator()

Returns an iterator over the elements in this set, in ascending order.

abstract 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.

abstract E pollFirst()

Retrieves and removes the first (lowest) element, or returns null if this set is empty.

abstract E pollLast()

Retrieves and removes the last (highest) element, or returns null if this set is empty.

abstract SortedSet<E> subSet(E fromElement, E toElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements greater or equal to the start element but less than the end element.

Equivalent to subSet(fromElement, true, toElement, false).

abstract 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.

abstract 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.

abstract SortedSet<E> tailSet(E fromElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements greater or equal to the start element.

Equivalent to tailSet(fromElement, true).

Inherited methods

From interface java.util.SortedSet
From interface java.util.Set
From interface java.util.Collection
From interface java.lang.Iterable

Public methods

ceiling

Added in API level 9
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.

Parameters
e E: the value to match
Returns
E the least element greater than or equal to 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 does not permit null elements

descendingIterator

Added in API level 9
Iterator<E> descendingIterator ()

Returns an iterator over the elements in this set, in descending order. Equivalent in effect to descendingSet().iterator().

Returns
Iterator<E> an iterator over the elements in this set, in descending order

descendingSet

Added in API level 9
NavigableSet<E> descendingSet ()

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.

Returns
NavigableSet<E> a reverse order view of this set

floor

Added in API level 9
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.

Parameters
e E: the value to match
Returns
E the greatest element less than or equal to 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 does not permit null elements

headSet

Added in API level 11
SortedSet<E> headSet (E toElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements less than the end element. The returned SortedSet is backed by this SortedSet so changes to one set are reflected by the other.

Equivalent to headSet(toElement, false).

Parameters
toElement E: the end element.
Returns
SortedSet<E> a subset where the elements are less than end.
Throws
ClassCastException
NullPointerException
IllegalArgumentException na

headSet

Added in API level 9
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. 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.

Parameters
toElement E: high endpoint of the returned set
inclusive boolean: true if the high endpoint is to be included in the returned view
Returns
NavigableSet<E> a view of the portion of this set whose elements are 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 does not permit null elements
IllegalArgumentException if this set itself has a restricted range, and toElement lies outside the bounds of the range

higher

Added in API level 9
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.

Parameters
e E: the value to match
Returns
E the least element greater than 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 does not permit null elements

iterator

Added in API level 11
Iterator<E> iterator ()

Returns an iterator over the elements in this set, in ascending order.

Returns
Iterator<E> an iterator over the elements in this set, in ascending order

lower

Added in API level 9
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.

Parameters
e E: the value to match
Returns
E the greatest element less than 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 does not permit null elements

pollFirst

Added in API level 9
E pollFirst ()

Retrieves and removes the first (lowest) element, or returns null if this set is empty.

Returns
E the first element, or null if this set is empty

pollLast

Added in API level 9
E pollLast ()

Retrieves and removes the last (highest) element, or returns null if this set is empty.

Returns
E the last element, or null if this set is empty

subSet

Added in API level 11
SortedSet<E> subSet (E fromElement, 
                E toElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements greater or equal to the start element but less than the end element. The returned SortedSet is backed by this SortedMap so changes to one set are reflected by the other.

Equivalent to subSet(fromElement, true, toElement, false).

Parameters
fromElement E: the start element.
toElement E: the end element.
Returns
SortedSet<E> a subset where the elements are greater or equal to start and less than end.
Throws
ClassCastException
NullPointerException
IllegalArgumentException

subSet

Added in API level 9
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. If fromElement and toElement are equal, the returned set is empty unless fromExclusive and toExclusive 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.

Parameters
fromElement E: low endpoint of the returned set
fromInclusive boolean: true if the low endpoint is to be included in the returned view
toElement E: high endpoint of the returned set
toInclusive boolean: true if the high endpoint is to be included in the returned view
Returns
NavigableSet<E> 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 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.

tailSet

Added in API level 9
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. 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.

Parameters
fromElement E: low endpoint of the returned set
inclusive boolean: true if the low endpoint is to be included in the returned view
Returns
NavigableSet<E> 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 does not permit null elements
IllegalArgumentException if this set itself has a restricted range, and fromElement lies outside the bounds of the range

tailSet

Added in API level 11
SortedSet<E> tailSet (E fromElement)

Returns a SortedSet of the specified portion of this SortedSet which contains elements greater or equal to the start element. The returned SortedSet is backed by this SortedSet so changes to one set are reflected by the other.

Equivalent to tailSet(fromElement, true).

Parameters
fromElement E: the start element.
Returns
SortedSet<E> a subset where the elements are greater or equal to start .
Throws
ClassCastException
NullPointerException
IllegalArgumentException
This site uses cookies to store your preferences for site-specific language and display options.

Hooray!

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.