TreeSet.java revision 3203
2027N/A * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved. 0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 0N/A * This code is free software; you can redistribute it and/or modify it 0N/A * under the terms of the GNU General Public License version 2 only, as 0N/A * published by the Free Software Foundation. Oracle designates this 0N/A * particular file as subject to the "Classpath" exception as provided 0N/A * by Oracle in the LICENSE file that accompanied this code. 0N/A * This code is distributed in the hope that it will be useful, but WITHOUT 0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 0N/A * version 2 for more details (a copy is included in the LICENSE file that 0N/A * accompanied this code). 0N/A * You should have received a copy of the GNU General Public License version 0N/A * 2 along with this work; if not, write to the Free Software Foundation, 1472N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1472N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 0N/A * or visit www.oracle.com if you need additional information or have any 1879N/A * A {@link NavigableSet} implementation based on a {@link TreeMap}. 1879N/A * The elements are ordered using their {@linkplain Comparable natural 1879N/A * ordering}, or by a {@link Comparator} provided at set creation 1879N/A * time, depending on which constructor is used. 1879N/A * <p>This implementation provides guaranteed log(n) time cost for the basic 1879N/A * operations ({@code add}, {@code remove} and {@code contains}). 1879N/A * <p>Note that the ordering maintained by a set (whether or not an explicit 1879N/A * comparator is provided) must be <i>consistent with equals</i> if it is to 1879N/A * correctly implement the {@code Set} interface. (See {@code Comparable} 1879N/A * or {@code Comparator} for a precise definition of <i>consistent with 1879N/A * equals</i>.) This is so because the {@code Set} interface is defined in 1879N/A * terms of the {@code equals} operation, but a {@code TreeSet} instance 1879N/A * performs all element comparisons using its {@code compareTo} (or 1879N/A * {@code compare}) method, so two elements that are deemed equal by this method 0N/A * are, from the standpoint of the set, equal. The behavior of a set 0N/A * <i>is</i> well-defined even if its ordering is inconsistent with equals; it 0N/A * just fails to obey the general contract of the {@code Set} interface. 0N/A * <p><strong>Note that this implementation is not synchronized.</strong> 0N/A * If multiple threads access a tree set concurrently, and at least one 0N/A * of the threads modifies the set, it <i>must</i> be synchronized 0N/A * externally. This is typically accomplished by synchronizing on some 0N/A * object that naturally encapsulates the set. 0N/A * If no such object exists, the set should be "wrapped" using the 0N/A * {@link Collections#synchronizedSortedSet Collections.synchronizedSortedSet} 0N/A * method. This is best done at creation time, to prevent accidental 1522N/A * unsynchronized access to the set: <pre> 0N/A * SortedSet s = Collections.synchronizedSortedSet(new TreeSet(...));</pre> 113N/A * <p>The iterators returned by this class's {@code iterator} method are 2027N/A * <i>fail-fast</i>: if the set is modified at any time after the iterator is 113N/A * created, in any way except through the iterator's own {@code remove} 0N/A * method, the iterator will throw a {@link ConcurrentModificationException}. 2027N/A * Thus, in the face of concurrent modification, the iterator fails quickly 1485N/A * and cleanly, rather than risking arbitrary, non-deterministic behavior at 2027N/A * an undetermined time in the future. 2027N/A * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed 1485N/A * as it is, generally speaking, impossible to make any hard guarantees in the 2027N/A * presence of unsynchronized concurrent modification. Fail-fast iterators 0N/A * throw {@code ConcurrentModificationException} on a best-effort basis. 726N/A * Therefore, it would be wrong to write a program that depended on this 726N/A * exception for its correctness: <i>the fail-fast behavior of iterators 726N/A * should be used only to detect bugs.</i> 0N/A * <p>This class is a member of the 941N/A * Java Collections Framework</a>. 0N/A * @param <E> the type of elements maintained by this set 0N/A * @author Josh Bloch 0N/A // Dummy value to associate with an Object in the backing Map 0N/A * Constructs a set backed by the specified navigable map. 0N/A * Constructs a new, empty tree set, sorted according to the 0N/A * natural ordering of its elements. All elements inserted into 0N/A * the set must implement the {@link Comparable} interface. 0N/A * Furthermore, all such elements must be <i>mutually 0N/A * comparable</i>: {@code e1.compareTo(e2)} must not throw a 0N/A * {@code ClassCastException} for any elements {@code e1} and 726N/A * {@code e2} in the set. If the user attempts to add an element 726N/A * to the set that violates this constraint (for example, the user 0N/A * attempts to add a string element to a set whose elements are 0N/A * integers), the {@code add} call will throw a 0N/A * {@code ClassCastException}. 0N/A * Constructs a new, empty tree set, sorted according to the specified 0N/A * comparator. All elements inserted into the set must be <i>mutually 0N/A * comparable</i> by the specified comparator: {@code comparator.compare(e1, 0N/A * e2)} must not throw a {@code ClassCastException} for any elements 0N/A * {@code e1} and {@code e2} in the set. If the user attempts to add 0N/A * an element to the set that violates this constraint, the 0N/A * {@code add} call will throw a {@code ClassCastException}. 0N/A * @param comparator the comparator that will be used to order this set. 0N/A * If {@code null}, the {@linkplain Comparable natural 0N/A * ordering} of the elements will be used. 2745N/A * Constructs a new tree set containing the elements in the specified 0N/A * collection, sorted according to the <i>natural ordering</i> of its 0N/A * elements. All elements inserted into the set must implement the 0N/A * {@link Comparable} interface. Furthermore, all such elements must be 0N/A * <i>mutually comparable</i>: {@code e1.compareTo(e2)} must not throw a 1879N/A * {@code ClassCastException} for any elements {@code e1} and 1879N/A * @param c collection whose elements will comprise the new set 1879N/A * @throws ClassCastException if the elements in {@code c} are 1879N/A * not {@link Comparable}, or are not mutually comparable 1879N/A * @throws NullPointerException if the specified collection is null 2073N/A * Constructs a new tree set containing the same elements and 1879N/A * using the same ordering as the specified sorted set. 0N/A * @param s sorted set whose elements will comprise the new set 0N/A * @throws NullPointerException if the specified sorted set is null 0N/A * Returns an iterator over the elements in this set in ascending order. 0N/A * @return an iterator over the elements in this set in ascending order 0N/A * Returns an iterator over the elements in this set in descending order. 0N/A * @return an iterator over the elements in this set in descending order * Returns the number of elements in this set (its cardinality). * @return the number of elements in this set (its cardinality) * Returns {@code true} if this set contains no elements. * @return {@code true} if this set contains no elements * Returns {@code true} if this set contains the specified element. * More formally, returns {@code true} if and only if this set * contains an element {@code e} such that * <tt>(o==null ? e==null : o.equals(e))</tt>. * @param o object to be checked for containment in this set * @return {@code 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 the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * Adds the specified element to this set if it is not already present. * More formally, adds the specified element {@code e} to this set if * the set contains no element {@code e2} such that * <tt>(e==null ? e2==null : e.equals(e2))</tt>. * If this set already contains the element, the call leaves the set * unchanged and returns {@code false}. * @param e element to be added to this set * @return {@code true} if this set did not already contain the specified * @throws ClassCastException if the specified object cannot be compared * with the elements currently in this set * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements public boolean add(E e) {
* Removes the specified element from this set if it is present. * More formally, removes an element {@code e} such that * <tt>(o==null ? e==null : o.equals(e))</tt>, * if this set contains such an element. Returns {@code true} if * this set contained the element (or equivalently, if this set * changed as a result of the call). (This set will not contain the * element once the call returns.) * @param o object to be removed from this set, if present * @return {@code true} if this set contained the specified element * @throws ClassCastException if the specified object cannot be compared * with the elements currently in this set * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * Removes all of the elements from this set. * The set will be empty after this call returns. * Adds all of the elements in the specified collection to this set. * @param c collection containing elements to be added to this set * @return {@code true} if this set changed as a result of the call * @throws ClassCastException if the elements provided cannot be compared * with the elements currently in the set * @throws NullPointerException if the specified collection is null or * if any element is null and this set uses natural ordering, or * its comparator does not permit null elements // Use linear-time version if applicable * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code fromElement} or {@code toElement} * is null and this set uses natural ordering, or its comparator * does not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code toElement} is null and * this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code fromElement} is null and * this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code fromElement} or * {@code toElement} is null and this set uses natural ordering, * or its comparator does not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code toElement} is null * and this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if {@code fromElement} is null * and this set uses natural ordering, or its comparator does * not permit null elements * @throws IllegalArgumentException {@inheritDoc} * @throws NoSuchElementException {@inheritDoc} * @throws NoSuchElementException {@inheritDoc} // NavigableSet API methods * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * @throws ClassCastException {@inheritDoc} * @throws NullPointerException if the specified element is null * and this set uses natural ordering, or its comparator * does not permit null elements * Returns a shallow copy of this {@code TreeSet} instance. (The elements * themselves are not cloned.) * @return a shallow copy of this set * Save the state of the {@code TreeSet} instance to a stream (that is, * @serialData Emits the comparator used to order this set, or * {@code null} if it obeys its elements' natural ordering * (Object), followed by the size of the set (the number of * elements it contains) (int), followed by all of its * elements (each an Object) in order (as determined by the * set's Comparator, or by the elements' natural ordering if * the set has no Comparator). // Write out any hidden stuff // Write out all elements in the proper order. * Reconstitute the {@code TreeSet} instance from a stream (that is, // Read in any hidden stuff // Create backing TreeMap