--- jsr166/src/jsr166x/ConcurrentSkipListSet.java 2005/03/08 17:51:57 1.6 +++ jsr166/src/jsr166x/ConcurrentSkipListSet.java 2012/12/29 23:55:19 1.15 @@ -1,10 +1,10 @@ /* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain, as explained at - * http://creativecommons.org/licenses/publicdomain + * http://creativecommons.org/publicdomain/zero/1.0/ */ -package jsr166x; +package jsr166x; import java.util.*; import java.util.concurrent.*; @@ -60,11 +60,11 @@ public class ConcurrentSkipListSet * fields of underlying map, but enables this field to be declared * final, which is necessary for thread safety. */ - private final ConcurrentSkipListMap m; + private final ConcurrentSkipListMap m; /** * Constructs a new, empty set, sorted according to the elements' natural - * order. + * order. */ public ConcurrentSkipListSet() { m = new ConcurrentSkipListMap(); @@ -72,7 +72,7 @@ public class ConcurrentSkipListSet /** * Constructs a new, empty set, sorted according to the specified - * comparator. + * comparator. * * @param c the comparator that will be used to sort this set. A * null value indicates that the elements' natural @@ -86,12 +86,12 @@ public class ConcurrentSkipListSet * Constructs a new set containing the elements in the specified * collection, sorted according to the elements' natural order. * - * @param c The elements that will comprise the new set. + * @param c The elements that will comprise the new set * * @throws ClassCastException if the elements in the specified - * collection are not comparable, or are not mutually comparable. + * collection are not comparable, or are not mutually comparable * @throws NullPointerException if the specified collection is - * null. + * null */ public ConcurrentSkipListSet(Collection c) { m = new ConcurrentSkipListMap(); @@ -102,9 +102,9 @@ public class ConcurrentSkipListSet * Constructs a new set containing the same elements as the specified * sorted set, sorted according to the same ordering. * - * @param s sorted set whose elements will comprise the new set. + * @param s sorted set whose elements will comprise the new set * @throws NullPointerException if the specified sorted set is - * null. + * null */ public ConcurrentSkipListSet(SortedSet s) { m = new ConcurrentSkipListMap(s.comparator()); @@ -115,15 +115,15 @@ public class ConcurrentSkipListSet * Returns a shallow copy of this set. (The elements themselves * are not cloned.) * - * @return a shallow copy of this set. + * @return a shallow copy of this set */ public Object clone() { ConcurrentSkipListSet clone = null; - try { - clone = (ConcurrentSkipListSet) super.clone(); - } catch (CloneNotSupportedException e) { - throw new InternalError(); - } + try { + clone = (ConcurrentSkipListSet) super.clone(); + } catch (CloneNotSupportedException e) { + throw new InternalError(); + } clone.m.initialize(); clone.addAll(this); @@ -146,88 +146,88 @@ public class ConcurrentSkipListSet * will be inaccurate. Thus, this method is typically not very * useful in concurrent applications. * - * @return the number of elements in this set. + * @return the number of elements in this set */ public int size() { - return m.size(); + return m.size(); } /** * Returns true if this set contains no elements. - * @return true if this set contains no elements. + * @return true if this set contains no elements */ public boolean isEmpty() { - return m.isEmpty(); + return m.isEmpty(); } /** * Returns true if this set contains the specified element. * - * @param o the object to be checked for containment in this set. - * @return true if this set contains the specified element. + * @param o the object to be checked for containment in this set + * @return true if this set contains the specified element * * @throws ClassCastException if the specified object cannot be compared - * with the elements currently in the set. - * @throws NullPointerException if o is null. + * with the elements currently in the set + * @throws NullPointerException if o is null */ public boolean contains(Object o) { - return m.containsKey(o); + return m.containsKey(o); } /** * Adds the specified element to this set if it is not already present. * - * @param o element to be added to this set. + * @param o element to be added to this set * @return true if the set did not already contain the specified - * element. + * element * * @throws ClassCastException if the specified object cannot be compared - * with the elements currently in the set. - * @throws NullPointerException if o is null. + * with the elements currently in the set + * @throws NullPointerException if o is null */ public boolean add(E o) { - return m.putIfAbsent(o, Boolean.TRUE) == null; + return m.putIfAbsent(o, Boolean.TRUE) == null; } /** * Removes the specified element from this set if it is present. * - * @param o object to be removed from this set, if present. - * @return true if the set contained the specified element. + * @param o object to be removed from this set, if present + * @return true if the set contained the specified element * * @throws ClassCastException if the specified object cannot be compared - * with the elements currently in the set. - * @throws NullPointerException if o is null. + * with the elements currently in the set + * @throws NullPointerException if o is null */ public boolean remove(Object o) { - return m.removep(o); + return m.removep(o); } /** * Removes all of the elements from this set. */ public void clear() { - m.clear(); + m.clear(); } /** * Returns an iterator over the elements in this set. The elements * are returned in ascending order. * - * @return an iterator over the elements in this set. + * @return an iterator over the elements in this set */ public Iterator iterator() { - return m.keyIterator(); + return m.keyIterator(); } /** * Returns an iterator over the elements in this set. The elements * are returned in descending order. * - * @return an iterator over the elements in this set. + * @return an iterator over the elements in this set */ public Iterator descendingIterator() { - return m.descendingKeyIterator(); + return m.descendingKeyIterator(); } /* ---------------- AbstractSet Overrides -------------- */ @@ -241,25 +241,25 @@ public class ConcurrentSkipListSet * equals method works properly across different implementations of the * set interface. * - * @param o Object to be compared for equality with this set. - * @return true if the specified Object is equal to this set. + * @param o Object to be compared for equality with this set + * @return true if the specified Object is equal to this set */ public boolean equals(Object o) { // Override AbstractSet version to avoid calling size() - if (o == this) - return true; - if (!(o instanceof Set)) - return false; - Collection c = (Collection) o; + if (o == this) + return true; + if (!(o instanceof Set)) + return false; + Collection c = (Collection) o; try { return containsAll(c) && c.containsAll(this); - } catch(ClassCastException unused) { + } catch (ClassCastException unused) { return false; - } catch(NullPointerException unused) { + } catch (NullPointerException unused) { return false; } } - + /** * Removes from this set all of its elements that are contained in * the specified collection. If the specified collection is also @@ -267,13 +267,13 @@ public class ConcurrentSkipListSet * value is the asymmetric set difference of the two sets. * * @param c collection that defines which elements will be removed from - * this set. - * @return true if this set changed as a result of the call. - * + * this set + * @return true if this set changed as a result of the call + * * @throws ClassCastException if the types of one or more elements in this * set are incompatible with the specified collection * @throws NullPointerException if the specified collection, or any - * of its elements are null. + * of its elements are null */ public boolean removeAll(Collection c) { // Override AbstractSet version to avoid unnecessary call to size() @@ -283,18 +283,18 @@ public class ConcurrentSkipListSet modified = true; return modified; } - + /* ---------------- Relational operations -------------- */ /** * Returns an element greater than or equal to the given element, or * null if there is no such element. - * + * * @param o the value to match * @return an element greater than or equal to given element, or - * null if there is no such element. + * null if there is no such element * @throws ClassCastException if o cannot be compared with the elements - * currently in the set. + * currently in the set * @throws NullPointerException if o is null */ public E ceiling(E o) { @@ -304,13 +304,13 @@ public class ConcurrentSkipListSet /** * Returns an element strictly less than the given element, or * null if there is no such element. - * + * * @param o the value to match * @return the greatest element less than the given element, or - * null if there is no such element. + * null if there is no such element * @throws ClassCastException if o cannot be compared with the elements - * currently in the set. - * @throws NullPointerException if o is null. + * currently in the set + * @throws NullPointerException if o is null */ public E lower(E o) { return m.lowerKey(o); @@ -319,13 +319,13 @@ public class ConcurrentSkipListSet /** * Returns an element less than or equal to the given element, or * null if there is no such element. - * + * * @param o the value to match * @return the greatest element less than or equal to given - * element, or null if there is no such element. + * element, or null if there is no such element * @throws ClassCastException if o cannot be compared with the elements - * currently in the set. - * @throws NullPointerException if o is null. + * currently in the set + * @throws NullPointerException if o is null */ public E floor(E o) { return m.floorKey(o); @@ -334,13 +334,13 @@ public class ConcurrentSkipListSet /** * Returns an element strictly greater than the given element, or * null if there is no such element. - * + * * @param o the value to match * @return the least element greater than the given element, or - * null if there is no such element. + * null if there is no such element * @throws ClassCastException if o cannot be compared with the elements - * currently in the set. - * @throws NullPointerException if o is null. + * currently in the set + * @throws NullPointerException if o is null */ public E higher(E o) { return m.higherKey(o); @@ -349,7 +349,7 @@ public class ConcurrentSkipListSet /** * Retrieves and removes the first (lowest) element. * - * @return the least element, or null if empty. + * @return the least element, or null if empty */ public E pollFirst() { return m.pollFirstKey(); @@ -358,7 +358,7 @@ public class ConcurrentSkipListSet /** * Retrieves and removes the last (highest) element. * - * @return the last element, or null if empty. + * @return the last element, or null if empty */ public E pollLast() { return m.pollLastKey(); @@ -373,7 +373,7 @@ public class ConcurrentSkipListSet * if this set uses its elements natural ordering. * * @return the comparator used to order this set, or null - * if this set uses its elements natural ordering. + * if this set uses its elements natural ordering */ public Comparator comparator() { return m.comparator(); @@ -382,8 +382,8 @@ public class ConcurrentSkipListSet /** * Returns the first (lowest) element currently in this set. * - * @return the first (lowest) element currently in this set. - * @throws NoSuchElementException sorted set is empty. + * @return the first (lowest) element currently in this set + * @throws NoSuchElementException sorted set is empty */ public E first() { return m.firstKey(); @@ -392,8 +392,8 @@ public class ConcurrentSkipListSet /** * Returns the last (highest) element currently in this set. * - * @return the last (highest) element currently in this set. - * @throws NoSuchElementException sorted set is empty. + * @return the last (highest) element currently in this set + * @throws NoSuchElementException sorted set is empty */ public E last() { return m.lastKey(); @@ -407,40 +407,40 @@ public class ConcurrentSkipListSet * fromElement and toElement are equal, the returned * sorted set is empty.) The returned sorted set is backed by this set, * so changes in the returned sorted set are reflected in this set, and - * vice-versa. - * @param fromElement low endpoint (inclusive) of the subSet. - * @param toElement high endpoint (exclusive) of the subSet. + * vice-versa. + * @param fromElement low endpoint (inclusive) of the subSet + * @param toElement high endpoint (exclusive) of the subSet * @return a view of the portion of this set whose elements range from - * fromElement, inclusive, to toElement, - * exclusive. + * 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). + * using natural ordering) * @throws IllegalArgumentException if fromElement is - * greater than toElement. + * greater than toElement * @throws NullPointerException if fromElement or - * toElement is null. + * toElement is null */ public NavigableSet subSet(E fromElement, E toElement) { - return new ConcurrentSkipListSubSet(m, fromElement, toElement); + return new ConcurrentSkipListSubSet(m, fromElement, toElement); } /** * Returns a view of the portion of this set whose elements are strictly * less than toElement. The returned sorted set is backed by * this set, so changes in the returned sorted set are reflected in this - * set, and vice-versa. - * @param toElement high endpoint (exclusive) of the headSet. + * 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. + * less than toElement * @throws ClassCastException if toElement 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. + * if toElement does not implement Comparable) + * @throws NullPointerException if toElement is null */ public NavigableSet headSet(E toElement) { - return new ConcurrentSkipListSubSet(m, null, toElement); + return new ConcurrentSkipListSubSet(m, null, toElement); } @@ -449,17 +449,17 @@ public class ConcurrentSkipListSet * greater than or equal to fromElement. The returned * sorted set is backed by this set, so changes in the returned * sorted set are reflected in this set, and vice-versa. - * @param fromElement low endpoint (inclusive) of the tailSet. + * @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. + * 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. + * Comparable) + * @throws NullPointerException if fromElement is null */ public NavigableSet tailSet(E fromElement) { - return new ConcurrentSkipListSubSet(m, fromElement, null); + return new ConcurrentSkipListSubSet(m, fromElement, null); } /** @@ -471,25 +471,24 @@ public class ConcurrentSkipListSet * in {@link IllegalArgumentException}. Instances of this class are * constructed only using the subSet, headSet, and * tailSet methods of their underlying sets. - * */ - static class ConcurrentSkipListSubSet - extends AbstractSet + static class ConcurrentSkipListSubSet + extends AbstractSet implements NavigableSet, java.io.Serializable { private static final long serialVersionUID = -7647078645896651609L; /** The underlying submap */ private final ConcurrentSkipListMap.ConcurrentSkipListSubMap s; - + /** - * Creates a new submap. + * Creates a new submap. * @param fromElement inclusive least value, or null if from start * @param toElement exclusive upper bound or null if to end * @throws IllegalArgumentException if fromElement and toElement - * nonnull and fromElement greater than toElement + * non-null and fromElement greater than toElement */ - ConcurrentSkipListSubSet(ConcurrentSkipListMap map, + ConcurrentSkipListSubSet(ConcurrentSkipListMap map, E fromElement, E toElement) { s = new ConcurrentSkipListMap.ConcurrentSkipListSubMap (map, fromElement, toElement); @@ -500,7 +499,7 @@ public class ConcurrentSkipListSet public NavigableSet subSet(E fromElement, E toElement) { if (!s.inOpenRange(fromElement) || !s.inOpenRange(toElement)) throw new IllegalArgumentException("element out of range"); - return new ConcurrentSkipListSubSet(s.getMap(), + return new ConcurrentSkipListSubSet(s.getMap(), fromElement, toElement); } @@ -508,15 +507,15 @@ public class ConcurrentSkipListSet E least = s.getLeast(); if (!s.inOpenRange(toElement)) throw new IllegalArgumentException("element out of range"); - return new ConcurrentSkipListSubSet(s.getMap(), + return new ConcurrentSkipListSubSet(s.getMap(), least, toElement); } - + public NavigableSet tailSet(E fromElement) { E fence = s.getFence(); if (!s.inOpenRange(fromElement)) throw new IllegalArgumentException("element out of range"); - return new ConcurrentSkipListSubSet(s.getMap(), + return new ConcurrentSkipListSubSet(s.getMap(), fromElement, fence); } @@ -539,14 +538,14 @@ public class ConcurrentSkipListSet public Iterator descendingIterator() { return s.descendingKeySet().iterator(); } - public E pollFirst() { + public E pollFirst() { Map.Entry e = s.pollFirstEntry(); - return (e == null)? null : e.getKey(); + return (e == null) ? null : e.getKey(); } public E pollLast() { Map.Entry e = s.pollLastEntry(); - return (e == null)? null : e.getKey(); + return (e == null) ? null : e.getKey(); } } -} +}