NavigableSet JDK 1.6)

Description

public interface NavigableSet

A SortedSet extended with navigation methods reporting closest matches for given search targets.

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.

This interface is a member of the Java Collections Framework.

See also:

Methods

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public 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.

Returns the least element in this set greater than or equal to
the given element, or null if there is no such element.
Returns: the least element greater than or equal to {@code e}, or {@code null} if there is no such element
Parameters:
- e - the value to match
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

public Iterator< E> descendingIterator ()

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

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

public NavigableSet< E> descendingSet ()

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

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: a reverse order view of this set

public 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.

Returns the greatest element in this set less than or equal to
the given element, or null if there is no such element.
Returns: the greatest element less than or equal to {@code e}, or {@code null} if there is no such element
Parameters:
- e - the value to match
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

public SortedSet< E> headSet ( E toElement) [Specified in SortedSet]

Returns a view of the portion of this set whose elements are strictly less than toElement.

public 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.

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.
Returns: a view of the portion of this set whose elements are less than (or equal to, if {@code inclusive} is true) {@code toElement}
Parameters:
- toElement - high endpoint of the returned set
- inclusive - {@code true} if the high endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code toElement} is not compatible with this set's comparator (or, if the set has no comparator, if {@code toElement} does not implement {@link Comparable}). Implementations may, but are not required to, throw this exception if {@code toElement} cannot be compared to elements currently in the set.
- NullPointerException - if {@code toElement} is null and this set does not permit null elements
- IllegalArgumentException - if this set itself has a restricted range, and {@code toElement} lies outside the bounds of the range

public 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.

Returns the least element in this set strictly greater than the
given element, or null if there is no such element.
Returns: the least element greater than {@code e}, or {@code null} if there is no such element
Parameters:
- e - the value to match
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

public Iterator< E> iterator ()

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

public 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.

Returns the greatest element in this set strictly less than the
given element, or null if there is no such element.
Returns: the greatest element less than {@code e}, or {@code null} if there is no such element
Parameters:
- e - the value to match
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

public E pollFirst ()

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

Retrieves and removes the first (lowest) element,
or returns null if this set is empty.
Returns: the first element, or {@code null} if this set is empty

public E pollLast ()

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

Retrieves and removes the last (highest) element,
or returns null if this set is empty.
Returns: the last element, or {@code null} if this set is empty

public 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.

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.
Returns: a view of the portion of this set whose elements range from {@code fromElement}, inclusive, to {@code toElement}, exclusive
Parameters:
- fromElement - low endpoint of the returned set
- fromInclusive - {@code true} if the low endpoint is to be included in the returned view
- toElement - high endpoint of the returned set
- toInclusive - {@code true} if the high endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code fromElement} and {@code 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 {@code fromElement} or {@code toElement} cannot be compared to elements currently in the set.
- NullPointerException - if {@code fromElement} or {@code toElement} is null and this set does not permit null elements
- IllegalArgumentException - if {@code fromElement} is greater than {@code toElement}; or if this set itself has a restricted range, and {@code fromElement} or {@code toElement} lies outside the bounds of the range.

public SortedSet< E> subSet ( E fromElement, E toElement) [Specified in SortedSet]

Returns a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive.

public SortedSet< E> tailSet ( E fromElement) [Specified in SortedSet]

Returns a view of the portion of this set whose elements are greater than or equal to fromElement.

public 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.

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.
Returns: a view of the portion of this set whose elements are greater than or equal to {@code fromElement}
Parameters:
- fromElement - low endpoint of the returned set
- inclusive - {@code true} if the low endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code fromElement} is not compatible with this set's comparator (or, if the set has no comparator, if {@code fromElement} does not implement {@link Comparable}). Implementations may, but are not required to, throw this exception if {@code fromElement} cannot be compared to elements currently in the set.
- NullPointerException - if {@code fromElement} is null and this set does not permit null elements
- IllegalArgumentException - if this set itself has a restricted range, and {@code fromElement} lies outside the bounds of the range