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/* |
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* Written by Doug Lea and Josh Bloch with assistance from members of JCP |
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* JSR-166 Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package java.util; |
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/** |
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* A {@link SortedSet} extended with navigation methods reporting |
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* closest matches for given search targets. Methods {@code lower}, |
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* {@code floor}, {@code ceiling}, and {@code higher} return elements |
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* closest matches for given search targets. Methods {@link #lower}, |
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* {@link #floor}, {@link #ceiling}, and {@link #higher} return elements |
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* respectively less than, less than or equal, greater than or equal, |
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* and greater than a given element, returning {@code null} if there |
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* is no such element. A {@code NavigableSet} may be accessed and |
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* traversed in either ascending or descending order. The {@code |
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* descendingSet} method returns a view of the set with the senses of |
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* all relational and directional methods inverted. The performance of |
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* ascending operations and views is likely to be faster than that of |
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* descending ones. This interface additionally defines methods |
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* {@code pollFirst} and {@code pollLast} that return and remove the |
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* lowest and highest element, if one exists, else returning {@code |
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* null}. Methods {@code subSet}, {@code headSet}, |
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* and {@code tailSet} differ from the like-named {@code |
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* SortedSet} methods in accepting additional arguments describing |
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* whether lower and upper bounds are inclusive versus exclusive. |
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* Subsets of any {@code NavigableSet} must implement the {@code |
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* NavigableSet} interface. |
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* is no such element. |
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* |
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* <p> The return values of navigation methods may be ambiguous in |
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* <p>A {@code NavigableSet} may be accessed and traversed in either |
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* ascending or descending order. The {@link #descendingSet} method |
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* returns a view of the set with the senses of all relational and |
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* directional methods inverted. The performance of ascending |
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* operations and views is likely to be faster than that of descending |
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* ones. This interface additionally defines methods {@link |
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* #pollFirst} and {@link #pollLast} that return and remove the lowest |
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* and highest element, if one exists, else returning {@code null}. |
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* Methods |
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* {@link #subSet(Object, boolean, Object, boolean) subSet(E, boolean, E, boolean)}, |
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* {@link #headSet(Object, boolean) headSet(E, boolean)}, and |
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* {@link #tailSet(Object, boolean) tailSet(E, boolean)} |
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* differ from the like-named {@code SortedSet} methods in accepting |
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* additional arguments describing whether lower and upper bounds are |
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* inclusive versus exclusive. Subsets of any {@code NavigableSet} |
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* must implement the {@code NavigableSet} interface. |
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* |
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* <p>The return values of navigation methods may be ambiguous in |
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* implementations that permit {@code null} elements. However, even |
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* in this case the result can be disambiguated by checking |
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* {@code contains(null)}. To avoid such issues, implementations of |
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* {@code null} elements. (Note that sorted sets of {@link |
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* Comparable} elements intrinsically do not permit {@code null}.) |
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* |
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* <p>Methods |
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* {@link #subSet(Object, Object) subSet(E, E)}, |
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* {@link #headSet(Object) headSet(E)}, and |
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* {@link #tailSet(Object) tailSet(E)} |
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* are specified to return {@code SortedSet} to allow existing |
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* implementations of {@code SortedSet} to be compatibly retrofitted to |
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* implement {@code NavigableSet}, but extensions and implementations |
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* of this interface are encouraged to override these methods to return |
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* {@code NavigableSet}. |
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* |
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* <p>This interface is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @author Doug Lea |
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Iterator<E> iterator(); |
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/** |
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* Returns a {@link NavigableSet} view of the elements contained in this |
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* set in descending order. The descending set is backed by this set, so |
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* changes to the set are reflected in the descending set, and vice-versa. |
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* If either set is modified while an iteration over the other set is in |
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* progress (except through the iterator's own {@code remove} operation), |
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* the results of the iteration are undefined. |
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* Returns a reverse order view of the elements contained in this set. |
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* The descending set is backed by this set, so changes to the set are |
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* reflected in the descending set, and vice-versa. If either set is |
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* modified while an iteration over either set is in progress (except |
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* through the iterator's own {@code remove} operation), the results of |
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* the iteration are undefined. |
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* |
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* <p>The returned set has an ordering equivalent to |
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* {@link Collections#reverseOrder(Comparator) Collections.reverseOrder}{@code (comparator())}. |
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* The expression {@code s.descendingSet().descendingSet()} returns a |
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* view of {@code s} essentially equivalent to {@code s}. |
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* |
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* @return a navigable set view of the elements contained in this set, |
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* sorted in descending order |
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* @return a reverse order view of this set |
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*/ |
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NavigableSet<E> descendingSet(); |
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/** |
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* Returns an iterator over the elements in this set, in descending order. |
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* Equivalent in effect to <tt>descendingSet().iterator()</tt>. |
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* Equivalent in effect to {@code descendingSet().iterator()}. |
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* |
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* @return an iterator over the elements in this set, in descending order |
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*/ |
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* Returns a view of the portion of this set whose elements range from |
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* {@code fromElement} to {@code toElement}. If {@code fromElement} and |
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* {@code toElement} are equal, the returned set is empty unless {@code |
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* fromExclusive} and {@code toExclusive} are both true. The returned set |
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* fromInclusive} and {@code toInclusive} are both true. The returned set |
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* is backed by this set, so changes in the returned set are reflected in |
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* this set, and vice-versa. The returned set supports all optional set |
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* operations that this set supports. |
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NavigableSet<E> tailSet(E fromElement, boolean inclusive); |
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/** |
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* Equivalent to {@code subSet(fromElement, true, toElement, false)} |
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* but with a return type conforming to the {@code SortedSet} interface. |
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* {@inheritDoc} |
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* |
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* <p>{@inheritDoc} |
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* <p>Equivalent to {@code subSet(fromElement, true, toElement, false)}. |
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* |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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SortedSet<E> subSet(E fromElement, E toElement); |
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/** |
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* Equivalent to {@code headSet(toElement, false)} |
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* but with a return type conforming to the {@code SortedSet} interface. |
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* {@inheritDoc} |
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* |
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* <p>{@inheritDoc} |
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* <p>Equivalent to {@code headSet(toElement, false)}. |
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* |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
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SortedSet<E> headSet(E toElement); |
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/** |
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* Equivalent to {@code tailSet(fromElement, true)} |
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* but with a return type conforming to the {@code SortedSet} interface. |
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* {@inheritDoc} |
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* |
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* <p>{@inheritDoc} |
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* <p>Equivalent to {@code tailSet(fromElement, true)}. |
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* |
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* @throws ClassCastException {@inheritDoc} |
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* @throws NullPointerException {@inheritDoc} |
