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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/publicdomain/zero/1.0/ |
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*/ |
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|
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package java.util; |
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|
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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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* 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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* |
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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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* this interface are encouraged to <em>not</em> permit insertion 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}/../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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* @author Josh Bloch |
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* @param <E> the type of elements maintained by this set |
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* @since 1.6 |
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*/ |
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public interface NavigableSet<E> extends SortedSet<E> { |
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/** |
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* Returns the greatest element in this set strictly less than the |
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* given element, or {@code null} if there is no such element. |
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* |
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* @param e the value to match |
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* @return the greatest element less than {@code e}, |
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* or {@code null} if there is no such element |
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* @throws ClassCastException if the specified element cannot be |
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* compared with the elements currently in the set |
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* @throws NullPointerException if the specified element is null |
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* and this set does not permit null elements |
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*/ |
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E lower(E e); |
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|
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/** |
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* Returns the greatest element in this set less than or equal to |
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* the given element, or {@code null} if there is no such element. |
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* |
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* @param e the value to match |
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* @return the greatest element less than or equal to {@code e}, |
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* or {@code null} if there is no such element |
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* @throws ClassCastException if the specified element cannot be |
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* compared with the elements currently in the set |
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* @throws NullPointerException if the specified element is null |
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* and this set does not permit null elements |
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*/ |
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E floor(E e); |
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|
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/** |
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* Returns the least element in this set greater than or equal to |
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* the given element, or {@code null} if there is no such element. |
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* |
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* @param e the value to match |
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* @return the least element greater than or equal to {@code e}, |
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* or {@code null} if there is no such element |
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* @throws ClassCastException if the specified element cannot be |
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* compared with the elements currently in the set |
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* @throws NullPointerException if the specified element is null |
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* and this set does not permit null elements |
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*/ |
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E ceiling(E e); |
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|
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/** |
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* Returns the least element in this set strictly greater than the |
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* given element, or {@code null} if there is no such element. |
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* |
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* @param e the value to match |
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* @return the least element greater than {@code e}, |
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* or {@code null} if there is no such element |
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* @throws ClassCastException if the specified element cannot be |
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* compared with the elements currently in the set |
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* @throws NullPointerException if the specified element is null |
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* and this set does not permit null elements |
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*/ |
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E higher(E e); |
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|
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/** |
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* Retrieves and removes the first (lowest) element, |
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* or returns {@code null} if this set is empty. |
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* |
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* @return the first element, or {@code null} if this set is empty |
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*/ |
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E pollFirst(); |
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|
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/** |
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* Retrieves and removes the last (highest) element, |
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* or returns {@code null} if this set is empty. |
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* |
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* @return the last element, or {@code null} if this set is empty |
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*/ |
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E pollLast(); |
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|
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/** |
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* Returns an iterator over the elements in this set, in ascending order. |
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* |
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* @return an iterator over the elements in this set, in ascending order |
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*/ |
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Iterator<E> iterator(); |
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|
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/** |
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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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* <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>. |
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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 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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/** |
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* Returns an iterator over the elements in this set, in descending order. |
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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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Iterator<E> descendingIterator(); |
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|
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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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* 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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* |
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* <p>The returned set will throw an {@code IllegalArgumentException} |
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* on an attempt to insert an element outside its range. |
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* |
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* @param fromElement low endpoint of the returned set |
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* @param fromInclusive {@code true} if the low endpoint |
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* is to be included in the returned view |
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* @param toElement high endpoint of the returned set |
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* @param toInclusive {@code true} if the high endpoint |
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* is to be included in the returned view |
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* @return a view of the portion of this set whose elements range from |
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* {@code fromElement}, inclusive, to {@code toElement}, exclusive |
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* @throws ClassCastException if {@code fromElement} and |
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* {@code toElement} cannot be compared to one another using this |
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* set's comparator (or, if the set has no comparator, using |
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* natural ordering). Implementations may, but are not required |
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* to, throw this exception if {@code fromElement} or |
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* {@code toElement} cannot be compared to elements currently in |
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* the set. |
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* @throws NullPointerException if {@code fromElement} or |
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* {@code toElement} is null and this set does |
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* not permit null elements |
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* @throws IllegalArgumentException if {@code fromElement} is |
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* greater than {@code toElement}; or if this set itself |
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* has a restricted range, and {@code fromElement} or |
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* {@code toElement} lies outside the bounds of the range. |
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*/ |
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NavigableSet<E> subSet(E fromElement, boolean fromInclusive, |
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E toElement, boolean toInclusive); |
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|
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/** |
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* Returns a view of the portion of this set whose elements are less than |
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* (or equal to, if {@code inclusive} is true) {@code toElement}. The |
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* returned set is backed by this set, so changes in the returned set are |
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* reflected in this set, and vice-versa. The returned set supports all |
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* optional set operations that this set supports. |
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* |
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* <p>The returned set will throw an {@code IllegalArgumentException} |
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* on an attempt to insert an element outside its range. |
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* |
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* @param toElement high endpoint of the returned set |
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* @param inclusive {@code true} if the high endpoint |
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* is to be included in the returned view |
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* @return a view of the portion of this set whose elements are less than |
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* (or equal to, if {@code inclusive} is true) {@code toElement} |
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* @throws ClassCastException if {@code toElement} is not compatible |
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* with this set's comparator (or, if the set has no comparator, |
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* if {@code toElement} does not implement {@link Comparable}). |
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* Implementations may, but are not required to, throw this |
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* exception if {@code toElement} cannot be compared to elements |
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* currently in the set. |
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* @throws NullPointerException if {@code toElement} is null and |
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* this set does not permit null elements |
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* @throws IllegalArgumentException if this set itself has a |
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* restricted range, and {@code toElement} lies outside the |
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* bounds of the range |
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*/ |
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NavigableSet<E> headSet(E toElement, boolean inclusive); |
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|
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/** |
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* Returns a view of the portion of this set whose elements are greater |
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* than (or equal to, if {@code inclusive} is true) {@code fromElement}. |
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* The returned set is backed by this set, so changes in the returned set |
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* are reflected in this set, and vice-versa. The returned set supports |
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* all optional set operations that this set supports. |
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* |
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* <p>The returned set will throw an {@code IllegalArgumentException} |
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* on an attempt to insert an element outside its range. |
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* |
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* @param fromElement low endpoint of the returned set |
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* @param inclusive {@code true} if the low endpoint |
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* is to be included in the returned view |
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* @return a view of the portion of this set whose elements are greater |
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* than or equal to {@code fromElement} |
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* @throws ClassCastException if {@code fromElement} is not compatible |
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* with this set's comparator (or, if the set has no comparator, |
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* if {@code fromElement} does not implement {@link Comparable}). |
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* Implementations may, but are not required to, throw this |
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* exception if {@code fromElement} cannot be compared to elements |
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* currently in the set. |
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* @throws NullPointerException if {@code fromElement} is null |
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* and this set does not permit null elements |
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* @throws IllegalArgumentException if this set itself has a |
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* restricted range, and {@code fromElement} lies outside the |
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* bounds of the range |
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*/ |
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NavigableSet<E> tailSet(E fromElement, boolean inclusive); |
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|
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/** |
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* {@inheritDoc} |
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* |
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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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* @throws IllegalArgumentException {@inheritDoc} |
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*/ |
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SortedSet<E> subSet(E fromElement, E toElement); |
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|
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/** |
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* {@inheritDoc} |
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* |
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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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* @throws IllegalArgumentException {@inheritDoc} |
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na */ |
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SortedSet<E> headSet(E toElement); |
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|
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/** |
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* {@inheritDoc} |
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* |
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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} |
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* @throws IllegalArgumentException {@inheritDoc} |
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*/ |
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SortedSet<E> tailSet(E fromElement); |
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} |