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Comparing jsr166/src/main/java/util/TreeSet.java (file contents):
Revision 1.6 by jsr166, Mon Apr 18 05:18:29 2005 UTC vs.
Revision 1.20 by jsr166, Tue Feb 7 20:54:24 2006 UTC

#	Line 1 | Line 1
1		/*
2		* %W% %E%
3		*
4	<	* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
4	>	* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
5		* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6		*/
7
8	<	package java.util;
8	>	package java.util;
9
10		/**
11	<	* This class implements the <tt>Set</tt> interface, backed by a
12	<	* <tt>TreeMap</tt> instance.  This class guarantees that the sorted set will
13	<	* be in ascending element order, sorted according to the <i>natural order</i>
14	<	* of the elements (see <tt>Comparable</tt>), or by the comparator provided at
15	<	* set creation time, depending on which constructor is used.<p>
11	>	* A {@link NavigableSet} implementation based on a {@link TreeMap}.
12	>	* The elements are ordered using their {@linkplain Comparable natural
13	>	* ordering}, or by a {@link Comparator} provided at set creation
14	>	* time, depending on which constructor is used.
15		*
16	<	* This implementation provides guaranteed log(n) time cost for the basic
17	<	* operations (<tt>add</tt>, <tt>remove</tt> and <tt>contains</tt>).<p>
16	>	* <p>This implementation provides guaranteed log(n) time cost for the basic
17	>	* operations (<tt>add</tt>, <tt>remove</tt> and <tt>contains</tt>).
18		*
19	<	* Note that the ordering maintained by a set (whether or not an explicit
19	>	* <p>Note that the ordering maintained by a set (whether or not an explicit
20		* comparator is provided) must be <i>consistent with equals</i> if it is to
21		* correctly implement the <tt>Set</tt> interface.  (See <tt>Comparable</tt>
22		* or <tt>Comparator</tt> for a precise definition of <i>consistent with
23		* equals</i>.)  This is so because the <tt>Set</tt> interface is defined in
24		* terms of the <tt>equals</tt> operation, but a <tt>TreeSet</tt> instance
25	<	* performs all key comparisons using its <tt>compareTo</tt> (or
26	<	* <tt>compare</tt>) method, so two keys that are deemed equal by this method
25	>	* performs all element comparisons using its <tt>compareTo</tt> (or
26	>	* <tt>compare</tt>) method, so two elements that are deemed equal by this method
27		* are, from the standpoint of the set, equal.  The behavior of a set
28		* <i>is</i> well-defined even if its ordering is inconsistent with equals; it
29	<	* just fails to obey the general contract of the <tt>Set</tt> interface.<p>
29	>	* just fails to obey the general contract of the <tt>Set</tt> interface.
30		*
31	<	* <b>Note that this implementation is not synchronized.</b> If multiple
32	<	* threads access a set concurrently, and at least one of the threads modifies
33	<	* the set, it <i>must</i> be synchronized externally.  This is typically
34	<	* accomplished by synchronizing on some object that naturally encapsulates
35	<	* the set.  If no such object exists, the set should be "wrapped" using the
36	<	* <tt>Collections.synchronizedSet</tt> method.  This is best done at creation
37	<	* time, to prevent accidental unsynchronized access to the set: <pre>
38	<	*     SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));
39	<	* </pre><p>
31	>	* <p><strong>Note that this implementation is not synchronized.</strong>
32	>	* If multiple threads access a tree set concurrently, and at least one
33	>	* of the threads modifies the set, it <i>must</i> be synchronized
34	>	* externally.  This is typically accomplished by synchronizing on some
35	>	* object that naturally encapsulates the set.
36	>	* If no such object exists, the set should be "wrapped" using the
37	>	* {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet}
38	>	* method.  This is best done at creation time, to prevent accidental
39	>	* unsynchronized access to the set: <pre>
40	>	*   SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre>
41		*
42	<	* The Iterators returned by this class's <tt>iterator</tt> method are
42	>	* <p>The iterators returned by this class's <tt>iterator</tt> method are
43		* <i>fail-fast</i>: if the set is modified at any time after the iterator is
44		* created, in any way except through the iterator's own <tt>remove</tt>
45	<	* method, the iterator will throw a <tt>ConcurrentModificationException</tt>.
45	>	* method, the iterator will throw a {@link ConcurrentModificationException}.
46		* Thus, in the face of concurrent modification, the iterator fails quickly
47		* and cleanly, rather than risking arbitrary, non-deterministic behavior at
48		* an undetermined time in the future.
#	Line 53 | Line 53 | package java.util;
53		* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
54		* Therefore, it would be wrong to write a program that depended on this
55		* exception for its correctness:   <i>the fail-fast behavior of iterators
56	<	* should be used only to detect bugs.</i><p>
56	>	* should be used only to detect bugs.</i>
57		*
58	<	* This class is a member of the
58	>	* <p>This class is a member of the
59		* <a href="{@docRoot}/../guide/collections/index.html">
60		* Java Collections Framework</a>.
61		*
62	+	* @param <E> the type of elements maintained by this set
63	+	*
64		* @author  Josh Bloch
65		* @version %I%, %G%
66		* @see     Collection
#	Line 66 | Line 68 | package java.util;
68		* @see     HashSet
69		* @see     Comparable
70		* @see     Comparator
69	–	* @see     Collections#synchronizedSortedSet(SortedSet)
71		* @see     TreeMap
72		* @since   1.2
73		*/
#	Line 81 | Line 82 | public class TreeSet<E>
82		private static final Object PRESENT = new Object();
83
84		/**
85	<	* Constructs a set backed by the specified sorted map.
85	>	* Constructs a set backed by the specified navigable map.
86		*/
87		private TreeSet(NavigableMap<E,Object> m) {
88		this.m = m;
89		}
90
91		/**
92	<	* Constructs a new, empty set, sorted according to the elements' natural
93	<	* order.  All elements inserted into the set must implement the
94	<	* <tt>Comparable</tt> interface.  Furthermore, all such elements must be
95	<	* <i>mutually comparable</i>: <tt>e1.compareTo(e2)</tt> must not throw a
92	>	* Constructs a new, empty tree set, sorted according to the
93	>	* natural ordering of its elements.  All elements inserted into
94	>	* the set must implement the {@link Comparable} interface.
95	>	* Furthermore, all such elements must be <i>mutually
96	>	* comparable</i>: <tt>e1.compareTo(e2)</tt> must not throw a
97		* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and
98	<	* <tt>e2</tt> in the set.  If the user attempts to add an element to the
99	<	* set that violates this constraint (for example, the user attempts to
100	<	* add a string element to a set whose elements are integers), the
101	<	* <tt>add(Object)</tt> call will throw a <tt>ClassCastException</tt>.
102	<	*
101	<	* @see Comparable
98	>	* <tt>e2</tt> in the set.  If the user attempts to add an element
99	>	* to the set that violates this constraint (for example, the user
100	>	* attempts to add a string element to a set whose elements are
101	>	* integers), the <tt>add(Object)</tt> call will throw a
102	>	* <tt>ClassCastException</tt>.
103		*/
104		public TreeSet() {
105		this(new TreeMap<E,Object>());
106		}
107
108		/**
109	<	* Constructs a new, empty set, sorted according to the specified
109	>	* Constructs a new, empty tree set, sorted according to the specified
110		* comparator.  All elements inserted into the set must be <i>mutually
111		* comparable</i> by the specified comparator: <tt>comparator.compare(e1,
112		* e2)</tt> must not throw a <tt>ClassCastException</tt> for any elements
#	Line 113 | Line 114 | public class TreeSet<E>
114		* an element to the set that violates this constraint, the
115		* <tt>add(Object)</tt> call will throw a <tt>ClassCastException</tt>.
116		*
117	<	* @param c the comparator that will be used to sort this set.  A
118	<	*        <tt>null</tt> value indicates that the elements' <i>natural
119	<	*        ordering</i> should be used.
117	>	* @param comparator the comparator that will be used to order this set.
118	>	*        If <tt>null</tt>, the {@linkplain Comparable natural
119	>	*        ordering} of the elements will be used.
120		*/
121	<	public TreeSet(Comparator<? super E> c) {
122	<	this(new TreeMap<E,Object>(c));
121	>	public TreeSet(Comparator<? super E> comparator) {
122	>	this(new TreeMap<E,Object>(comparator));
123		}
124
125		/**
126	<	* Constructs a new set containing the elements in the specified
127	<	* collection, sorted according to the elements' <i>natural order</i>.
128	<	* All keys inserted into the set must implement the <tt>Comparable</tt>
129	<	* interface.  Furthermore, all such keys must be <i>mutually
130	<	* comparable</i>: <tt>k1.compareTo(k2)</tt> must not throw a
131	<	* <tt>ClassCastException</tt> for any elements <tt>k1</tt> and
132	<	* <tt>k2</tt> in the set.
132	<	*
133	<	* @param c The elements that will comprise the new set.
126	>	* Constructs a new tree set containing the elements in the specified
127	>	* collection, sorted according to the <i>natural ordering</i> of its
128	>	* elements.  All elements inserted into the set must implement the
129	>	* {@link Comparable} interface.  Furthermore, all such elements must be
130	>	* <i>mutually comparable</i>: <tt>e1.compareTo(e2)</tt> must not throw a
131	>	* <tt>ClassCastException</tt> for any elements <tt>e1</tt> and
132	>	* <tt>e2</tt> in the set.
133		*
134	<	* @throws ClassCastException if the keys in the specified collection are
135	<	*         not comparable, or are not mutually comparable.
136	<	* @throws NullPointerException if the specified collection is null.
134	>	* @param c collection whose elements will comprise the new set
135	>	* @throws ClassCastException if the elements in <tt>c</tt> are
136	>	*         not {@link Comparable}, or are not mutually comparable
137	>	* @throws NullPointerException if the specified collection is null
138		*/
139		public TreeSet(Collection<? extends E> c) {
140		this();
#	Line 142 | Line 142 | public class TreeSet<E>
142		}
143
144		/**
145	<	* Constructs a new set containing the same elements as the specified
146	<	* sorted set, sorted according to the same ordering.
145	>	* Constructs a new tree set containing the same elements and
146	>	* using the same ordering as the specified sorted set.
147		*
148	<	* @param s sorted set whose elements will comprise the new set.
149	<	* @throws NullPointerException if the specified sorted set is null.
148	>	* @param s sorted set whose elements will comprise the new set
149	>	* @throws NullPointerException if the specified sorted set is null
150		*/
151		public TreeSet(SortedSet<E> s) {
152		this(s.comparator());
#	Line 154 | Line 154 | public class TreeSet<E>
154		}
155
156		/**
157	<	* Returns an iterator over the elements in this set.  The elements
158	<	* are returned in ascending order.
157	>	* Returns an iterator over the elements in this set in ascending order.
158		*
159	<	* @return an iterator over the elements in this set.
159	>	* @return an iterator over the elements in this set in ascending order
160		*/
161		public Iterator<E> iterator() {
162	<	return m.keySet().iterator();
162	>	return m.keySet().iterator();
163		}
164
165		/**
166	<	* Returns an iterator over the elements in this set.  The elements
168	<	* are returned in descending order.
166	>	* Returns an iterator over the elements in this set in descending order.
167		*
168	<	* @return an iterator over the elements in this set.
168	>	* @return an iterator over the elements in this set in descending order
169	>	* @since 1.6
170		*/
171		public Iterator<E> descendingIterator() {
172		return m.descendingKeySet().iterator();
#	Line 176 | Line 175 | public class TreeSet<E>
175		/**
176		* Returns the number of elements in this set (its cardinality).
177		*
178	<	* @return the number of elements in this set (its cardinality).
178	>	* @return the number of elements in this set (its cardinality)
179		*/
180		public int size() {
181		return m.size();
#	Line 185 | Line 184 | public class TreeSet<E>
184		/**
185		* Returns <tt>true</tt> if this set contains no elements.
186		*
187	<	* @return <tt>true</tt> if this set contains no elements.
187	>	* @return <tt>true</tt> if this set contains no elements
188		*/
189		public boolean isEmpty() {
190		return m.isEmpty();
#	Line 193 | Line 192 | public class TreeSet<E>
192
193		/**
194		* Returns <tt>true</tt> if this set contains the specified element.
195	+	* More formally, returns <tt>true</tt> if and only if this set
196	+	* contains an element <tt>e</tt> such that
197	+	* <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
198		*
199	<	* @param o the object to be checked for containment in this set.
200	<	* @return <tt>true</tt> if this set contains the specified element.
199	<	*
199	>	* @param o object to be checked for containment in this set
200	>	* @return <tt>true</tt> if this set contains the specified element
201		* @throws ClassCastException if the specified object cannot be compared
202	<	*            with the elements currently in the set.
203	<	* @throws NullPointerException if o is <tt>null</tt> and this map
204	<	* uses natural ordering and is non-empty, or its comparator does
205	<	* not tolerate <tt>null</tt> keys.
202	>	*         with the elements currently in the set
203	>	* @throws NullPointerException if the specified element is null
204	>	*         and this set uses natural ordering, or its comparator
205	>	*         does not permit null elements
206		*/
207		public boolean contains(Object o) {
208		return m.containsKey(o);
#	Line 209 | Line 210 | public class TreeSet<E>
210
211		/**
212		* Adds the specified element to this set if it is not already present.
213	<	*
214	<	* @param o element to be added to this set.
215	<	* @return <tt>true</tt> if the set did not already contain the specified
216	<	*         element.
217	<	*
213	>	* More formally, adds the specified element <tt>e</tt> to this set if
214	>	* the set contains no element <tt>e2</tt> such that
215	>	* <tt>(e==null&nbsp;?&nbsp;e2==null&nbsp;:&nbsp;e.equals(e2))</tt>.
216	>	* If this set already contains the element, the call leaves the set
217	>	* unchanged and returns <tt>false</tt>.
218	>	*
219	>	* @param e element to be added to this set
220	>	* @return <tt>true</tt> if this set did not already contain the specified
221	>	*         element
222		* @throws ClassCastException if the specified object cannot be compared
223	<	*            with the elements currently in the set.
224	<	* @throws NullPointerException if o is <tt>null</tt> and this map
225	<	* uses natural ordering and is non-empty, or its comparator does
226	<	* not tolerate <tt>null</tt> keys.
223	>	*         with the elements currently in this set
224	>	* @throws NullPointerException if the specified element is null
225	>	*         and this set uses natural ordering, or its comparator
226	>	*         does not permit null elements
227		*/
228	<	public boolean add(E o) {
229	<	return m.put(o, PRESENT)==null;
228	>	public boolean add(E e) {
229	>	return m.put(e, PRESENT)==null;
230		}
231
232		/**
233		* Removes the specified element from this set if it is present.
234	+	* More formally, removes an element <tt>e</tt> such that
235	+	* <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>,
236	+	* if this set contains such an element.  Returns <tt>true</tt> if
237	+	* this set contained the element (or equivalently, if this set
238	+	* changed as a result of the call).  (This set will not contain the
239	+	* element once the call returns.)
240		*
241	<	* @param o object to be removed from this set, if present.
242	<	* @return <tt>true</tt> if the set contained the specified element.
232	<	*
241	>	* @param o object to be removed from this set, if present
242	>	* @return <tt>true</tt> if this set contained the specified element
243		* @throws ClassCastException if the specified object cannot be compared
244	<	*            with the elements currently in the set.
245	<	* @throws NullPointerException if o is <tt>null</tt> and this map
246	<	* uses natural ordering and is non-empty, or its comparator does
247	<	* not tolerate <tt>null</tt> keys.
244	>	*         with the elements currently in this set
245	>	* @throws NullPointerException if the specified element is null
246	>	*         and this set uses natural ordering, or its comparator
247	>	*         does not permit null elements
248		*/
249		public boolean remove(Object o) {
250		return m.remove(o)==PRESENT;
#	Line 242 | Line 252 | public class TreeSet<E>
252
253		/**
254		* Removes all of the elements from this set.
255	+	* The set will be empty after this call returns.
256		*/
257		public void clear() {
258		m.clear();
#	Line 250 | Line 261 | public class TreeSet<E>
261		/**
262		* Adds all of the elements in the specified collection to this set.
263		*
264	<	* @param c elements to be added
265	<	* @return <tt>true</tt> if this set changed as a result of the call.
255	<	*
264	>	* @param c collection containing elements to be added to this set
265	>	* @return <tt>true</tt> if this set changed as a result of the call
266		* @throws ClassCastException if the elements provided cannot be compared
267	<	*            with the elements currently in the set.
268	<	* @throws NullPointerException if the specified collection is
269	<	* <tt>null</tt> or if any element is <tt>null</tt> and this map
270	<	* uses natural ordering, or its comparator does not tolerate
261	<	* <tt>null</tt> keys.
267	>	*         with the elements currently in the set
268	>	* @throws NullPointerException if the specified collection is null or
269	>	*         if any element is null and this set uses natural ordering, or
270	>	*         its comparator does not permit null elements
271		*/
272		public  boolean addAll(Collection<? extends E> c) {
273		// Use linear-time version if applicable
274		if (m.size()==0 && c.size() > 0 &&
275		c instanceof SortedSet &&
276		m instanceof TreeMap) {
277	<	SortedSet<Map.Entry<E, Object>> set = (SortedSet<Map.Entry<E, Object>>) (SortedSet) c;
277	>	SortedSet<? extends E> set = (SortedSet<? extends E>) c;
278		TreeMap<E,Object> map = (TreeMap<E, Object>) m;
279	<	Comparator<? super E> cc = (Comparator<E>) set.comparator();
279	>	Comparator<? super E> cc = (Comparator<? super E>) set.comparator();
280		Comparator<? super E> mc = map.comparator();
281		if (cc==mc || (cc != null && cc.equals(mc))) {
282		map.addAllForTreeSet(set, PRESENT);
#	Line 278 | Line 287 | public class TreeSet<E>
287		}
288
289		/**
290	<	* Returns a view of the portion of this set whose elements range
282	<	* from <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
283	<	* exclusive.  (If <tt>fromElement</tt> and <tt>toElement</tt> are
284	<	* equal, the returned navigable set is empty.)  The returned
285	<	* navigable set is backed by this set, so changes in the returned
286	<	* navigable set are reflected in this set, and vice-versa.  The
287	<	* returned navigable set supports all optional Set operations.<p>
288	<	*
289	<	* The navigable set returned by this method will throw an
290	<	* <tt>IllegalArgumentException</tt> if the user attempts to insert an
291	<	* element outside the specified range.<p>
292	<	*
293	<	* Note: this method always returns a <i>half-open range</i>
294	<	* (which includes its low endpoint but not its high endpoint).
295	<	* If you need a <i>closed range</i> (which includes both
296	<	* endpoints), and the element type allows for calculation of the
297	<	* successor of a specified value, merely request the subrange
298	<	* from <tt>lowEndpoint</tt> to <tt>successor(highEndpoint)</tt>.
299	<	* For example, suppose that <tt>s</tt> is a navigable set of
300	<	* strings.  The following idiom obtains a view containing all of
301	<	* the strings in <tt>s</tt> from <tt>low</tt> to <tt>high</tt>,
302	<	* inclusive:
303	<	* <pre> NavigableSet sub = s.navigableSubSet(low, high+"\0");
304	<	* </pre>
305	<	*
306	<	* A similar technique can be used to generate an <i>open range</i> (which
307	<	* contains neither endpoint).  The following idiom obtains a view
308	<	* containing all of the strings in <tt>s</tt> from <tt>low</tt> to
309	<	* <tt>high</tt>, exclusive: <pre>
310	<	*     NavigableSet sub = s.navigableSubSet(low+"\0", high);
311	<	* </pre>
312	<	*
313	<	* @param fromElement low endpoint (inclusive) of the range.
314	<	* @param toElement high endpoint (exclusive) of the range.
315	<	* @return a view of the portion of this set whose elements range from
316	<	*         <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
317	<	*         exclusive.
318	<	* @throws ClassCastException if <tt>fromElement</tt> and
319	<	*         <tt>toElement</tt> cannot be compared to one another using
320	<	*         this set's comparator (or, if the set has no comparator,
321	<	*         using natural ordering).
322	<	* @throws IllegalArgumentException if <tt>fromElement</tt> is greater than
323	<	*         <tt>toElement</tt>.
290	>	* @throws ClassCastException {@inheritDoc}
291		* @throws NullPointerException if <tt>fromElement</tt> or
292	<	*         <tt>toElement</tt> is <tt>null</tt> and this set uses natural
293	<	*         order, or its comparator does not tolerate <tt>null</tt>
294	<	*         elements.
292	>	*         <tt>toElement</tt> is null and this set uses natural ordering,
293	>	*         or its comparator does not permit null elements
294	>	* @throws IllegalArgumentException {@inheritDoc}
295	>	* @since 1.6
296		*/
297		public NavigableSet<E> navigableSubSet(E fromElement, E toElement) {
298		return new TreeSet<E>(m.navigableSubMap(fromElement, toElement));
299		}
300
301		/**
302	<	* Returns a view of the portion of this set whose elements are
303	<	* strictly less than <tt>toElement</tt>.  The returned navigable
304	<	* set is backed by this set, so changes in the returned navigable
305	<	* set are reflected in this set, and vice-versa.  The returned
306	<	* navigable set supports all optional set operations.<p>
307	<	*
340	<	* The navigable set returned by this method will throw an
341	<	* <tt>IllegalArgumentException</tt> if the user attempts to
342	<	* insert an element greater than or equal to
343	<	* <tt>toElement</tt>.<p>
344	<	*
345	<	* Note: this method always returns a view that does not contain
346	<	* its (high) endpoint.  If you need a view that does contain this
347	<	* endpoint, and the element type allows for calculation of the
348	<	* successor of a specified value, merely request a headSet
349	<	* bounded by <tt>successor(highEndpoint)</tt>.  For example,
350	<	* suppose that <tt>s</tt> is a navigable set of strings.  The
351	<	* following idiom obtains a view containing all of the strings in
352	<	* <tt>s</tt> that are less than or equal to <tt>high</tt>:
353	<	* <pre> NavigableSet head = s.navigableHeadSet(high+"\0");</pre>
354	<	*
355	<	* @param toElement high endpoint (exclusive) of the headSet.
356	<	* @return a view of the portion of this set whose elements are strictly
357	<	*         less than <tt>toElement</tt>.
358	<	* @throws ClassCastException if <tt>toElement</tt> is not compatible
359	<	*         with this set's comparator (or, if the set has no comparator,
360	<	*         if <tt>toElement</tt> does not implement <tt>Comparable</tt>).
361	<	* @throws IllegalArgumentException if this set is itself a subset,
362	<	*         and <tt>toElement</tt> is not within the
363	<	*         specified range of the subset.
364	<	* @throws NullPointerException if <tt>toElement</tt> is <tt>null</tt> and
365	<	*         this set uses natural ordering, or its comparator does
366	<	*         not tolerate <tt>null</tt> elements.
302	>	* @throws ClassCastException {@inheritDoc}
303	>	* @throws NullPointerException if <tt>toElement</tt> is null and
304	>	*         this set uses natural ordering, or its comparator does
305	>	*         not permit null elements
306	>	* @throws IllegalArgumentException {@inheritDoc}
307	>	* @since 1.6
308		*/
309		public NavigableSet<E> navigableHeadSet(E toElement) {
310		return new TreeSet<E>(m.navigableHeadMap(toElement));
311		}
312
313		/**
314	<	* Returns a view of the portion of this set whose elements are
315	<	* greater than or equal to <tt>fromElement</tt>.  The returned
316	<	* navigable set is backed by this set, so changes in the returned
317	<	* navigable set are reflected in this set, and vice-versa.  The
318	<	* returned navigable set supports all optional set operations.<p>
319	<	*
379	<	* The navigable set returned by this method will throw an
380	<	* <tt>IllegalArgumentException</tt> if the user attempts to insert an
381	<	* element less than <tt>fromElement</tt>.
382	<	*
383	<	* Note: this method always returns a view that contains its (low)
384	<	* endpoint.  If you need a view that does not contain this
385	<	* endpoint, and the element type allows for calculation of the
386	<	* successor of a specified value, merely request a tailSet
387	<	* bounded by <tt>successor(lowEndpoint)</tt>.  For example,
388	<	* suppose that <tt>s</tt> is a navigable set of strings.  The
389	<	* following idiom obtains a view containing all of the strings in
390	<	* <tt>s</tt> that are strictly greater than <tt>low</tt>:
391	<	* <pre>  NavigableSet tail = s.navigableTailSet(low+"\0");
392	<	* </pre>
393	<	*
394	<	* @param fromElement low endpoint (inclusive) of the tailSet.
395	<	* @return a view of the portion of this set whose elements are
396	<	*         greater than or equal to <tt>fromElement</tt>.
397	<	* @throws ClassCastException if <tt>fromElement</tt> is not compatible
398	<	*         with this set's comparator (or, if the set has no comparator,
399	<	*         if <tt>fromElement</tt> does not implement <tt>Comparable</tt>).
400	<	* @throws IllegalArgumentException if this set is itself a subset,
401	<	*         and <tt>fromElement</tt> is not within the
402	<	*         specified range of the subset.
403	<	* @throws NullPointerException if <tt>fromElement</tt> is <tt>null</tt>
404	<	*         and this set uses natural ordering, or its comparator does
405	<	*         not tolerate <tt>null</tt> elements.
314	>	* @throws ClassCastException {@inheritDoc}
315	>	* @throws NullPointerException if <tt>fromElement</tt> is null and
316	>	*         this set uses natural ordering, or its comparator does
317	>	*         not permit null elements
318	>	* @throws IllegalArgumentException {@inheritDoc}
319	>	* @since 1.6
320		*/
321		public NavigableSet<E> navigableTailSet(E fromElement) {
322		return new TreeSet<E>(m.navigableTailMap(fromElement));
323		}
324
411	–
325		/**
326	<	* Equivalent to <tt>navigableSubSet</tt> but with a return
327	<	* type conforming to the <tt>SortedSet</tt> interface.
328	<	* @param fromElement low endpoint (inclusive) of the range.
329	<	* @param toElement high endpoint (exclusive) of the range.
330	<	* @return a view of the portion of this set whose elements range from
331	<	*         <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>,
419	<	*         exclusive.
420	<	* @throws ClassCastException if <tt>fromElement</tt> and
421	<	*         <tt>toElement</tt> cannot be compared to one another using
422	<	*         this set's comparator (or, if the set has no comparator,
423	<	*         using natural ordering).
424	<	* @throws IllegalArgumentException if <tt>fromElement</tt> is greater than
425	<	*         <tt>toElement</tt>.
326	>	* Equivalent to {@link #navigableSubSet} but with a return type
327	>	* conforming to the <tt>SortedSet</tt> interface.
328	>	*
329	>	* <p>{@inheritDoc}
330	>	*
331	>	* @throws ClassCastException {@inheritDoc}
332		* @throws NullPointerException if <tt>fromElement</tt> or
333	<	*         <tt>toElement</tt> is <tt>null</tt> and this set uses natural
334	<	*         order, or its comparator does not tolerate <tt>null</tt>
335	<	*         elements.
333	>	*         <tt>toElement</tt> is null and this set uses natural ordering,
334	>	*         or its comparator does not permit null elements
335	>	* @throws IllegalArgumentException {@inheritDoc}
336		*/
337		public SortedSet<E> subSet(E fromElement, E toElement) {
338		return new TreeSet<E>(m.navigableSubMap(fromElement, toElement));
339		}
340
341		/**
342	<	* Equivalent to <tt>navigableHeadSet</tt> but with a return
343	<	* type conforming to the <tt>SortedSet</tt> interface.
342	>	* Equivalent to {@link #navigableHeadSet} but with a return type
343	>	* conforming to the <tt>SortedSet</tt> interface.
344	>	*
345	>	* <p>{@inheritDoc}
346		*
347	<	* @param toElement high endpoint (exclusive) of the headSet.
348	<	* @return a view of the portion of this set whose elements are strictly
349	<	*         less than <tt>toElement</tt>.
350	<	* @throws ClassCastException if <tt>toElement</tt> is not compatible
351	<	*         with this set's comparator (or, if the set has no comparator,
444	<	*         if <tt>toElement</tt> does not implement <tt>Comparable</tt>).
445	<	* @throws IllegalArgumentException if this set is itself a subset,
446	<	*         and <tt>toElement</tt> is not within the
447	<	*         specified range of the subset.
448	<	* @throws NullPointerException if <tt>toElement</tt> is <tt>null</tt> and
449	<	*         this set uses natural ordering, or its comparator does
450	<	*         not tolerate <tt>null</tt> elements.
347	>	* @throws ClassCastException {@inheritDoc}
348	>	* @throws NullPointerException if <tt>toElement</tt> is null
349	>	*         and this set uses natural ordering, or its comparator does
350	>	*         not permit null elements
351	>	* @throws IllegalArgumentException {@inheritDoc}
352		*/
353		public SortedSet<E> headSet(E toElement) {
354		return new TreeSet<E>(m.navigableHeadMap(toElement));
355		}
356
357		/**
358	<	* Equivalent to <tt>navigableTailSet</tt> but with a return
359	<	* type conforming to the <tt>SortedSet</tt> interface.
360	<	* @param fromElement low endpoint (inclusive) of the tailSet.
361	<	* @return a view of the portion of this set whose elements are
362	<	*         greater than or equal to <tt>fromElement</tt>.
363	<	* @throws ClassCastException if <tt>fromElement</tt> is not compatible
364	<	*         with this set's comparator (or, if the set has no comparator,
365	<	*         if <tt>fromElement</tt> does not implement <tt>Comparable</tt>).
366	<	* @throws IllegalArgumentException if this set is itself a subset,
367	<	*         and <tt>fromElement</tt> is not within the
467	<	*         specified range of the subset.
468	<	* @throws NullPointerException if <tt>fromElement</tt> is <tt>null</tt>
469	<	*         and this set uses natural ordering, or its comparator does
470	<	*         not tolerate <tt>null</tt> elements.
358	>	* Equivalent to {@link #navigableTailSet} but with a return type
359	>	* conforming to the <tt>SortedSet</tt> interface.
360	>	*
361	>	* <p>{@inheritDoc}
362	>	*
363	>	* @throws ClassCastException {@inheritDoc}
364	>	* @throws NullPointerException if <tt>fromElement</tt> is null
365	>	*         and this set uses natural ordering, or its comparator does
366	>	*         not permit null elements
367	>	* @throws IllegalArgumentException {@inheritDoc}
368		*/
369		public SortedSet<E> tailSet(E fromElement) {
370		return new TreeSet<E>(m.navigableTailMap(fromElement));
371		}
372
476	–	/**
477	–	* Returns the comparator used to order this sorted set, or <tt>null</tt>
478	–	* if this tree set uses its elements natural ordering.
479	–	*
480	–	* @return the comparator used to order this sorted set, or <tt>null</tt>
481	–	* if this tree set uses its elements natural ordering.
482	–	*/
373		public Comparator<? super E> comparator() {
374		return m.comparator();
375		}
376
377		/**
378	<	* Returns the first (lowest) element currently in this sorted set.
489	<	*
490	<	* @return the first (lowest) element currently in this sorted set.
491	<	* @throws    NoSuchElementException sorted set is empty.
378	>	* @throws NoSuchElementException {@inheritDoc}
379		*/
380		public E first() {
381		return m.firstKey();
382		}
383
384		/**
385	<	* Returns the last (highest) element currently in this sorted set.
499	<	*
500	<	* @return the last (highest) element currently in this sorted set.
501	<	* @throws    NoSuchElementException sorted set is empty.
385	>	* @throws NoSuchElementException {@inheritDoc}
386		*/
387		public E last() {
388		return m.lastKey();
#	Line 506 | Line 390 | public class TreeSet<E>
390
391		// NavigableSet API methods
392
393	+	/**
394	+	* @throws ClassCastException {@inheritDoc}
395	+	* @throws NullPointerException if the specified element is null
396	+	*         and this set uses natural ordering, or its comparator
397	+	*         does not permit null elements
398	+	* @since 1.6
399	+	*/
400	+	public E lower(E e) {
401	+	return m.lowerKey(e);
402	+	}
403
404		/**
405	<	* Returns an element greater than or equal to the given element, or
406	<	* <tt>null</tt> if there is no such element.
407	<	*
408	<	* @param o the value to match
409	<	* @return an element greater than or equal to given element, or
516	<	* <tt>null</tt> if there is no such element.
517	<	* @throws ClassCastException if o cannot be compared with the elements
518	<	*            currently in the set.
519	<	* @throws NullPointerException if o is <tt>null</tt> and this map
520	<	* uses natural ordering and is non-empty, or its comparator does
521	<	* not tolerate <tt>null</tt> keys.
522	<	*/
523	<	public E ceiling(E o) {
524	<	return m.ceilingKey(o);
525	<	}
526	<
527	<	/**
528	<	* Returns an element strictly less than the given element, or
529	<	* <tt>null</tt> if there is no such element.
530	<	*
531	<	* @param o the value to match
532	<	* @return the greatest element less than the given element, or
533	<	* <tt>null</tt> if there is no such element.
534	<	* @throws ClassCastException if o cannot be compared with the elements
535	<	*            currently in the set.
536	<	* @throws NullPointerException if o is <tt>null</tt> and this map
537	<	* uses natural ordering and is non-empty, or its comparator does
538	<	* not tolerate <tt>null</tt> keys.
539	<	*/
540	<	public E lower(E o) {
541	<	return m.lowerKey(o);
542	<	}
543	<
544	<	/**
545	<	* Returns an element less than or equal to the given element, or
546	<	* <tt>null</tt> if there is no such element.
547	<	*
548	<	* @param o the value to match
549	<	* @return the greatest element less than or equal to given
550	<	* element, or <tt>null</tt> if there is no such element.
551	<	* @throws ClassCastException if o cannot be compared with the elements
552	<	*            currently in the set.
553	<	* @throws NullPointerException if o is <tt>null</tt> and this map
554	<	* uses natural ordering and is non-empty, or its comparator does
555	<	* not tolerate <tt>null</tt> keys.
556	<	*/
557	<	public E floor(E o) {
558	<	return m.floorKey(o);
559	<	}
560	<
561	<	/**
562	<	* Returns an element strictly greater than the given element, or
563	<	* <tt>null</tt> if there is no such element.
564	<	*
565	<	* @param o the value to match
566	<	* @return the least element greater than the given element, or
567	<	* <tt>null</tt> if there is no such element.
568	<	* @throws ClassCastException if o cannot be compared with the elements
569	<	*            currently in the set.
570	<	* @throws NullPointerException if o is <tt>null</tt> and this map
571	<	* uses natural ordering and is non-empty, or its comparator does
572	<	* not tolerate <tt>null</tt> keys.
405	>	* @throws ClassCastException {@inheritDoc}
406	>	* @throws NullPointerException if the specified element is null
407	>	*         and this set uses natural ordering, or its comparator
408	>	*         does not permit null elements
409	>	* @since 1.6
410		*/
411	<	public E higher(E o) {
412	<	return m.higherKey(o);
411	>	public E floor(E e) {
412	>	return m.floorKey(e);
413		}
414
415		/**
416	<	* Retrieves and removes the first (lowest) element.
417	<	*
418	<	* @return the least element, or <tt>null</tt> if empty.
416	>	* @throws ClassCastException {@inheritDoc}
417	>	* @throws NullPointerException if the specified element is null
418	>	*         and this set uses natural ordering, or its comparator
419	>	*         does not permit null elements
420	>	* @since 1.6
421	>	*/
422	>	public E ceiling(E e) {
423	>	return m.ceilingKey(e);
424	>	}
425	>
426	>	/**
427	>	* @throws ClassCastException {@inheritDoc}
428	>	* @throws NullPointerException if the specified element is null
429	>	*         and this set uses natural ordering, or its comparator
430	>	*         does not permit null elements
431	>	* @since 1.6
432	>	*/
433	>	public E higher(E e) {
434	>	return m.higherKey(e);
435	>	}
436	>
437	>	/**
438	>	* @since 1.6
439		*/
440		public E pollFirst() {
441		Map.Entry<E,?> e = m.pollFirstEntry();
#	Line 586 | Line 443 | public class TreeSet<E>
443		}
444
445		/**
446	<	* Retrieves and removes the last (highest) element.
590	<	*
591	<	* @return the last element, or <tt>null</tt> if empty.
446	>	* @since 1.6
447		*/
448		public E pollLast() {
449		Map.Entry<E,?> e = m.pollLastEntry();
#	Line 599 | Line 454 | public class TreeSet<E>
454		* Returns a shallow copy of this <tt>TreeSet</tt> instance. (The elements
455		* themselves are not cloned.)
456		*
457	<	* @return a shallow copy of this set.
457	>	* @return a shallow copy of this set
458		*/
459		public Object clone() {
460		TreeSet<E> clone = null;
#	Line 619 | Line 474 | public class TreeSet<E>
474		* serialize it).
475		*
476		* @serialData Emits the comparator used to order this set, or
477	<	*             <tt>null</tt> if it obeys its elements' natural ordering
478	<	*             (Object), followed by the size of the set (the number of
479	<	*             elements it contains) (int), followed by all of its
480	<	*             elements (each an Object) in order (as determined by the
481	<	*             set's Comparator, or by the elements' natural ordering if
477	>	*             <tt>null</tt> if it obeys its elements' natural ordering
478	>	*             (Object), followed by the size of the set (the number of
479	>	*             elements it contains) (int), followed by all of its
480	>	*             elements (each an Object) in order (as determined by the
481	>	*             set's Comparator, or by the elements' natural ordering if
482		*             the set has no Comparator).
483		*/
484		private void writeObject(java.io.ObjectOutputStream s)
#	Line 652 | Line 507 | public class TreeSet<E>
507		s.defaultReadObject();
508
509		// Read in Comparator
510	<	Comparator<E> c = (Comparator<E>) s.readObject();
510	>	Comparator<? super E> c = (Comparator<? super E>) s.readObject();
511
512		// Create backing TreeMap
513		TreeMap<E,Object> tm;

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