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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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*/ |
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|
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package jsr166x; |
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import java.util.*; |
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|
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/** |
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* A {@link SortedSet} extended with methods reporting closest matches |
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* for given search targets. Methods <tt>lower</tt>, <tt>floor</tt>, |
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* <tt>ceiling</tt>, and <tt>higher</tt> return keys respectively |
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* less, less than or equal, greater than or equal, and greater than a |
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* given key, returning <tt>null</tt> if there is no such key. These |
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* methods are designed for locating, not traversing entries. To |
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* traverse, use view iterators and/or <tt>subset</tt>. This interface |
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* additionally defines methods <tt>pollFirst</tt> and |
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* <t>pollLast</tt> that return and remove the lowest and highest key, |
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* if one exists, else returning <tt>null</tt>. |
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* |
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* <p> The return values of these methods may be ambiguous in |
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* implementations that permit <tt>null</tt> elements. However, even |
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* in this case the result can be diambiguated by checking |
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* <tt>contains(null)</tt>. |
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* |
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* @author Doug Lea |
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* @param <E> the type of elements maintained by this set |
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*/ |
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public interface NavigableSet<E> extends SortedSet<E> { |
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/** |
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* Returns an element greater than or equal to the given element, or |
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* null if there is no such element. |
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* |
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* @param o the value to match |
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* @return an element greater than or equal to given element, or null |
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* if there is no such element. |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt> |
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* and this set deas not permit <tt>null</tt> elements |
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*/ |
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public E ceiling(E o); |
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|
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/** |
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* Returns an element strictly less than the given element, or null if |
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* there is no such element. |
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* |
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* @param o the value to match |
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* @return the greatest element less than the given element, or |
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* null if there is no such element. |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt> |
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* and this set deas not permit <tt>null</tt> elements |
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*/ |
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public E lower(E o); |
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|
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/** |
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* Returns an element less than or equal to the given element, or null |
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* if there is no such element. |
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* |
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* @param o the value to match |
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* @return the greatest element less than or equal to given |
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* element, or null if there is no such element. |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt>. |
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* and this set deas not permit <tt>null</tt> elements |
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*/ |
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public E floor(E o); |
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|
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/** |
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* Returns an element strictly greater than the given element, or null |
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* if there is no such element. |
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* |
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* @param o the value to match |
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* @return the least element greater than the given element, or |
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* null if there is no such element. |
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* @throws ClassCastException if o cannot be compared with the elements |
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* currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt> |
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* and this set deas not permit <tt>null</tt> elements |
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*/ |
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public E higher(E o); |
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|
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/** |
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* Retrieves and removes the first (lowest) element. |
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* |
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* @return the first element, or <tt>null</tt> if empty. |
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*/ |
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public 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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* |
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* @return the last element, or <tt>null</tt> if empty. |
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*/ |
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public E pollLast(); |
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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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* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive. (If |
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* <tt>fromElement</tt> and <tt>toElement</tt> are equal, the returned |
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* sorted set is empty.) The returned sorted set is backed by this set, |
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* so changes in the returned sorted set are reflected in this set, and |
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* vice-versa. |
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* @param fromElement low endpoint (inclusive) of the subSet. |
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* @param toElement high endpoint (exclusive) of the subSet. |
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* @return a view of the portion of this set whose elements range from |
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* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, |
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* exclusive. |
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* @throws ClassCastException if <tt>fromElement</tt> and |
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* <tt>toElement</tt> cannot be compared to one another using |
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* this set's comparator (or, if the set has no comparator, |
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* using natural ordering). |
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* @throws IllegalArgumentException if <tt>fromElement</tt> is |
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* greater than <tt>toElement</tt>. |
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* @throws NullPointerException if <tt>fromElement</tt> or |
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* <tt>toElement</tt> is <tt>null</tt>. |
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*/ |
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public NavigableSet<E> subSet(E fromElement, E toElement); |
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|
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/** |
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* Returns a view of the portion of this set whose elements are strictly |
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* less than <tt>toElement</tt>. The returned sorted set is backed by |
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* this set, so changes in the returned sorted set are reflected in this |
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* set, and vice-versa. |
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* @param toElement high endpoint (exclusive) of the headSet. |
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* @return a view of the portion of this set whose elements are strictly |
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* less than toElement. |
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* @throws ClassCastException if <tt>toElement</tt> is not compatible |
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* with this set's comparator (or, if the set has no comparator, |
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* if <tt>toElement</tt> does not implement <tt>Comparable</tt>). |
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* @throws NullPointerException if <tt>toElement</tt> is <tt>null</tt>. |
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*/ |
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public NavigableSet<E> headSet(E toElement); |
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|
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/** |
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* Returns a view of the portion of this set whose elements are |
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* greater than or equal to <tt>fromElement</tt>. The returned |
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* sorted set is backed by this set, so changes in the returned |
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* sorted set are reflected in this set, and vice-versa. |
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* @param fromElement low endpoint (inclusive) of the tailSet. |
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* @return a view of the portion of this set whose elements are |
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* greater than or equal to <tt>fromElement</tt>. |
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* @throws ClassCastException if <tt>fromElement</tt> is not |
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* compatible with this set's comparator (or, if the set has no |
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* comparator, if <tt>fromElement</tt> does not implement |
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* <tt>Comparable</tt>). |
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* @throws NullPointerException if <tt>fromElement</tt> is <tt>null</tt>. |
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*/ |
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public NavigableSet<E> tailSet(E fromElement); |
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} |
