--- jsr166/src/main/java/util/NavigableSet.java 2005/05/02 08:35:49 1.5
+++ jsr166/src/main/java/util/NavigableSet.java 2006/04/20 20:34:37 1.16
@@ -1,6 +1,6 @@
/*
- * Written by Doug Lea with assistance from members of JCP JSR-166
- * Expert Group and released to the public domain, as explained at
+ * Written by Doug Lea and Josh Bloch with assistance from members of JCP
+ * JSR-166 Expert Group and released to the public domain, as explained at
* http://creativecommons.org/licenses/publicdomain
*/
@@ -8,169 +8,236 @@ package java.util;
/**
* A {@link SortedSet} extended with navigation methods reporting
- * closest matches for given search targets. Methods lower,
- * floor, ceiling, and higher return keys
+ * closest matches for given search targets. Methods lower},
+ * {@code floor}, {@code ceiling}, and {@code higher} return elements
* respectively less than, less than or equal, greater than or equal,
- * and greater than a given key, returning null if there is
- * no such key. A NavigableSet may be viewed and traversed
- * in either ascending or descending order. The Collection
- * iterator method returns an ascending Iterator and
- * the additional method descendingIterator returns
- * descending iterator. The performance of ascending traversals is
- * likely to be faster than descending traversals. This interface
- * additionally defines methods pollFirst and
- * pollLast that return and remove the lowest and highest key,
- * if one exists, else returning null.
- * Methods navigableSubSet, navigableHeadSet, and
- * navigableTailSet differ from the similarly named
- * SortedSet methods only in that the returned sets
- * are guaranteed to obey the NavigableSet interface.
+ * and greater than a given element, returning {@code null} if there
+ * is no such element. A {@code NavigableSet} may be accessed and
+ * traversed in either ascending or descending order. The {@code
+ * 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
+ * {@code pollFirst} and {@code pollLast} that return and remove the
+ * lowest and highest element, if one exists, else returning {@code
+ * null}. Methods {@code subSet}, {@code headSet},
+ * and {@code tailSet} differ from the like-named {@code
+ * SortedSet} methods in accepting additional arguments describing
+ * whether lower and upper bounds are inclusive versus exclusive.
+ * Subsets of any {@code NavigableSet} must implement the {@code
+ * NavigableSet} interface.
*
* The return values of navigation methods may be ambiguous in
- * implementations that permit null elements. However, even
+ * implementations that permit {@code 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 not to permit insertion of
- * null elements. (Note that sorted sets of {@link
- * Comparable} elements intrinsically do not permit null.)
+ * {@code contains(null)}. To avoid such issues, implementations of
+ * this interface are encouraged to not permit insertion of
+ * {@code null} elements. (Note that sorted sets of {@link
+ * Comparable} elements intrinsically do not permit {@code null}.)
+ *
+ *
This interface is a member of the
+ *
+ * Java Collections Framework.
*
* @author Doug Lea
+ * @author Josh Bloch
* @param the type of elements maintained by this set
+ * @since 1.6
*/
public interface NavigableSet extends SortedSet {
/**
- * Returns an element greater than or equal to 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 {@code null} if there is no such element.
+ *
* @param e the value to match
- * @return an element greater than or equal to given element, or
- * null if there is no such element.
- * @throws ClassCastException if e cannot be compared with the elements
- * currently in the set.
- * @throws NullPointerException if e is null
- * and this set does not permit null elements
+ * @return the greatest element less than {@code e},
+ * or {@code null} if there is no such element
+ * @throws ClassCastException if the specified element cannot be
+ * compared with the elements currently in the set
+ * @throws NullPointerException if the specified element is null
+ * and this set does not permit null elements
*/
- E ceiling(E e);
+ E lower(E e);
/**
- * Returns an element strictly less than 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 {@code null} if there is no such element.
+ *
* @param e the value to match
- * @return the greatest element less than the given element, or
- * null if there is no such element.
- * @throws ClassCastException if e cannot be compared with the elements
- * currently in the set.
- * @throws NullPointerException if e is null
- * and this set does not permit null elements
+ * @return the greatest element less than or equal to {@code e},
+ * or {@code null} if there is no such element
+ * @throws ClassCastException if the specified element cannot be
+ * compared with the elements currently in the set
+ * @throws NullPointerException if the specified element is null
+ * and this set does not permit null elements
*/
- E lower(E e);
+ E floor(E e);
/**
- * Returns an element less 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 {@code null} if there is no such element.
+ *
* @param e the value to match
- * @return the greatest element less than or equal to given
- * element, or null if there is no such element.
- * @throws ClassCastException if e cannot be compared with the elements
- * currently in the set.
- * @throws NullPointerException if e is null.
- * and this set does not permit null elements
+ * @return the least element greater than or equal to {@code e},
+ * or {@code null} if there is no such element
+ * @throws ClassCastException if the specified element cannot be
+ * compared with the elements currently in the set
+ * @throws NullPointerException if the specified element is null
+ * and this set does not permit null elements
*/
- E floor(E e);
+ E ceiling(E e);
/**
- * Returns an element 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 {@code null} if there is no such element.
+ *
* @param e the value to match
- * @return the least element greater than the given element, or
- * null if there is no such element.
- * @throws ClassCastException if e cannot be compared with the elements
- * currently in the set.
- * @throws NullPointerException if e is null
- * and this set does not permit null elements
+ * @return the least element greater than {@code e},
+ * or {@code null} if there is no such element
+ * @throws ClassCastException if the specified element cannot be
+ * compared with the elements currently in the set
+ * @throws NullPointerException if the specified element is null
+ * and this set does not permit null elements
*/
E higher(E e);
/**
- * Retrieves and removes the first (lowest) element.
+ * Retrieves and removes the first (lowest) element,
+ * or returns {@code null} if this set is empty.
*
- * @return the first element, or null if empty.
+ * @return the first element, or {@code null} if this set is empty
*/
E pollFirst();
/**
- * Retrieves and removes the last (highest) element.
+ * Retrieves and removes the last (highest) element,
+ * or returns {@code null} if this set is empty.
*
- * @return the last element, or null if empty.
+ * @return the last element, or {@code null} if this set is empty
*/
E pollLast();
/**
- * Returns an iterator over the elements in this collection, in
- * descending order.
- *
- * @return an Iterator over the elements in this collection
+ * Returns an iterator over the elements in this set, in ascending order.
+ *
+ * @return an iterator over the elements in this set, in ascending order
+ */
+ Iterator iterator();
+
+ /**
+ * Returns a {@link NavigableSet} view of the elements contained in this
+ * set in descending order. 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 the other set is in
+ * in progress (except through the iterator's own {@code remove} operation),
+ * the results of the iteration are undefined.
+ *
+ * @return a navigable set view of the mappings contained in this set,
+ * sorted in descending order
+ */
+ NavigableSet descendingSet();
+
+ /**
+ * Returns an iterator over the elements in this set, in descending order.
+ * Equivalent in effect to descendingSet().iterator().
+ *
+ * @return an iterator over the elements in this set, in descending order
*/
Iterator descendingIterator();
/**
- * Returns a view of the portion of this set whose elements range
- * from fromElement, inclusive, to toElement,
- * exclusive. (If fromElement and toElement are
- * equal, the returned navigable set is empty.) The returned
- * navigable set is backed by this set, so changes in the returned
- * navigable set are reflected in this set, and vice-versa.
+ * Returns a view of the portion of this set whose elements range from
+ * {@code fromElement} to {@code toElement}. If {@code fromElement} and
+ * {@code toElement} are equal, the returned set is empty unless {@code
+ * fromExclusive} and {@code 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.
*
- * @param fromElement low endpoint (inclusive) of the subSet.
- * @param toElement high endpoint (exclusive) of the subSet.
+ * The returned set will throw an {@code IllegalArgumentException}
+ * on an attempt to insert an element outside its range.
+ *
+ * @param fromElement low endpoint of the returned set
+ * @param fromInclusive true if the low endpoint ({@code fromElement}) is
+ * to be included in the the returned view
+ * @param toElement high endpoint of the returned set
+ * @param toInclusive true if the high endpoint ({@code toElement}) is
+ * to be included in the the returned view
* @return 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).
- * @throws IllegalArgumentException if fromElement is
- * greater than toElement.
- * @throws NullPointerException if fromElement or
- * toElement is null
- * and this set does not permit null elements
- */
- NavigableSet navigableSubSet(E fromElement, E toElement);
-
- /**
- * Returns a view of the portion of this set whose elements are
- * strictly less than toElement. The returned navigable
- * set is backed by this set, so changes in the returned navigable
- * set are reflected in this set, and vice-versa.
- * @param toElement high endpoint (exclusive) of the headSet.
- * @return a view of the portion of this set whose elements are strictly
- * less than toElement.
- * @throws ClassCastException if toElement is not compatible
+ * {@code fromElement}, inclusive, to {@code toElement}, exclusive
+ * @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.
+ * @throws NullPointerException if {@code fromElement} or
+ * {@code toElement} is null and this set does
+ * not permit null elements
+ * @throws 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.
+ */
+ NavigableSet subSet(E fromElement, boolean fromInclusive,
+ E toElement, boolean toInclusive);
+
+ /**
+ * Returns a view of the portion of this set whose elements are less than
+ * (or equal to, if {@code inclusive} is true) {@code 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 {@code IllegalArgumentException}
+ * on an attempt to insert an element outside its range.
+ *
+ * @param toElement high endpoint of the returned set
+ * @param inclusive true if the high endpoint ({@code toElement}) is
+ * to be included in the the returned view
+ * @return a view of the portion of this set whose elements are less than
+ * (or equal to, if {@code inclusive} is true) {@code toElement}
+ * @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.
+ * @throws NullPointerException if {@code toElement} is null and
+ * this set does not permit null elements
+ * @throws IllegalArgumentException if this set itself has a
+ * restricted range, and {@code toElement} lies outside the
+ * bounds of the range
+ */
+ NavigableSet headSet(E toElement, boolean inclusive);
+
+ /**
+ * Returns a view of the portion of this set whose elements are greater
+ * than (or equal to, if {@code inclusive} is true) {@code 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 {@code IllegalArgumentException}
+ * on an attempt to insert an element outside its range.
+ *
+ * @param fromElement low endpoint of the returned set
+ * @param inclusive true if the low endpoint ({@code fromElement}) is
+ * to be included in the the returned view
+ * @return a view of the portion of this set whose elements are greater
+ * than or equal to {@code fromElement}
+ * @throws ClassCastException if {@code fromElement} is not compatible
* with this set's comparator (or, if the set has no comparator,
- * if toElement does not implement Comparable).
- * @throws NullPointerException if toElement is null
- * and this set does not permit null elements
- */
- NavigableSet navigableHeadSet(E toElement);
-
- /**
- * Returns a view of the portion of this set whose elements are
- * greater than or equal to fromElement. The returned
- * navigable set is backed by this set, so changes in the returned
- * navigable set are reflected in this set, and vice-versa.
- * @param fromElement low endpoint (inclusive) of the tailSet.
- * @return 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).
- * @throws NullPointerException if fromElement is null
- * and this set does not permit null elements
+ * 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.
+ * @throws NullPointerException if {@code fromElement} is null
+ * and this set does not permit null elements
+ * @throws IllegalArgumentException if this set itself has a
+ * restricted range, and {@code fromElement} lies outside the
+ * bounds of the range
*/
- NavigableSet navigableTailSet(E fromElement);
+ NavigableSet tailSet(E fromElement, boolean inclusive);
}