History

My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/java/util/Collection.java (1 of 18352 files). Show all

Unified · Split

java/pkg/java/util/Collection.java+456−0
@@ -0,0 +1,456 @@
1+/*
2+ * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
3+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4+ *
5+ * This code is free software; you can redistribute it and/or modify it
6+ * under the terms of the GNU General Public License version 2 only, as
7+ * published by the Free Software Foundation. Oracle designates this
8+ * particular file as subject to the "Classpath" exception as provided
9+ * by Oracle in the LICENSE file that accompanied this code.
10+ *
11+ * This code is distributed in the hope that it will be useful, but WITHOUT
12+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14+ * version 2 for more details (a copy is included in the LICENSE file that
15+ * accompanied this code).
16+ *
17+ * You should have received a copy of the GNU General Public License version
18+ * 2 along with this work; if not, write to the Free Software Foundation,
19+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20+ *
21+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22+ * or visit www.oracle.com if you need additional information or have any
23+ * questions.
24+ */
25+
26+package java.util;
27+
28+/**
29+ * The root interface in the <i>collection hierarchy</i>. A collection
30+ * represents a group of objects, known as its <i>elements</i>. Some
31+ * collections allow duplicate elements and others do not. Some are ordered
32+ * and others unordered. The JDK does not provide any <i>direct</i>
33+ * implementations of this interface: it provides implementations of more
34+ * specific subinterfaces like <tt>Set</tt> and <tt>List</tt>. This interface
35+ * is typically used to pass collections around and manipulate them where
36+ * maximum generality is desired.
37+ *
38+ * <p><i>Bags</i> or <i>multisets</i> (unordered collections that may contain
39+ * duplicate elements) should implement this interface directly.
40+ *
41+ * <p>All general-purpose <tt>Collection</tt> implementation classes (which
42+ * typically implement <tt>Collection</tt> indirectly through one of its
43+ * subinterfaces) should provide two "standard" constructors: a void (no
44+ * arguments) constructor, which creates an empty collection, and a
45+ * constructor with a single argument of type <tt>Collection</tt>, which
46+ * creates a new collection with the same elements as its argument. In
47+ * effect, the latter constructor allows the user to copy any collection,
48+ * producing an equivalent collection of the desired implementation type.
49+ * There is no way to enforce this convention (as interfaces cannot contain
50+ * constructors) but all of the general-purpose <tt>Collection</tt>
51+ * implementations in the Java platform libraries comply.
52+ *
53+ * <p>The "destructive" methods contained in this interface, that is, the
54+ * methods that modify the collection on which they operate, are specified to
55+ * throw <tt>UnsupportedOperationException</tt> if this collection does not
56+ * support the operation. If this is the case, these methods may, but are not
57+ * required to, throw an <tt>UnsupportedOperationException</tt> if the
58+ * invocation would have no effect on the collection. For example, invoking
59+ * the {@link #addAll(Collection)} method on an unmodifiable collection may,
60+ * but is not required to, throw the exception if the collection to be added
61+ * is empty.
62+ *
63+ * <p><a name="optional-restrictions"/>
64+ * Some collection implementations have restrictions on the elements that
65+ * they may contain. For example, some implementations prohibit null elements,
66+ * and some have restrictions on the types of their elements. Attempting to
67+ * add an ineligible element throws an unchecked exception, typically
68+ * <tt>NullPointerException</tt> or <tt>ClassCastException</tt>. Attempting
69+ * to query the presence of an ineligible element may throw an exception,
70+ * or it may simply return false; some implementations will exhibit the former
71+ * behavior and some will exhibit the latter. More generally, attempting an
72+ * operation on an ineligible element whose completion would not result in
73+ * the insertion of an ineligible element into the collection may throw an
74+ * exception or it may succeed, at the option of the implementation.
75+ * Such exceptions are marked as "optional" in the specification for this
76+ * interface.
77+ *
78+ * <p>It is up to each collection to determine its own synchronization
79+ * policy. In the absence of a stronger guarantee by the
80+ * implementation, undefined behavior may result from the invocation
81+ * of any method on a collection that is being mutated by another
82+ * thread; this includes direct invocations, passing the collection to
83+ * a method that might perform invocations, and using an existing
84+ * iterator to examine the collection.
85+ *
86+ * <p>Many methods in Collections Framework interfaces are defined in
87+ * terms of the {@link Object#equals(Object) equals} method. For example,
88+ * the specification for the {@link #contains(Object) contains(Object o)}
89+ * method says: "returns <tt>true</tt> if and only if this collection
90+ * contains at least one element <tt>e</tt> such that
91+ * <tt>(o==null ? e==null : o.equals(e))</tt>." This specification should
92+ * <i>not</i> be construed to imply that invoking <tt>Collection.contains</tt>
93+ * with a non-null argument <tt>o</tt> will cause <tt>o.equals(e)</tt> to be
94+ * invoked for any element <tt>e</tt>. Implementations are free to implement
95+ * optimizations whereby the <tt>equals</tt> invocation is avoided, for
96+ * example, by first comparing the hash codes of the two elements. (The
97+ * {@link Object#hashCode()} specification guarantees that two objects with
98+ * unequal hash codes cannot be equal.) More generally, implementations of
99+ * the various Collections Framework interfaces are free to take advantage of
100+ * the specified behavior of underlying {@link Object} methods wherever the
101+ * implementor deems it appropriate.
102+ *
103+ * <p>This interface is a member of the
104+ * <a href="{@docRoot}/../technotes/guides/collections/index.html">
105+ * Java Collections Framework</a>.
106+ *
107+ * @param <E> the type of elements in this collection
108+ *
109+ * @author Josh Bloch
110+ * @author Neal Gafter
111+ * @see Set
112+ * @see List
113+ * @see Map
114+ * @see SortedSet
115+ * @see SortedMap
116+ * @see HashSet
117+ * @see TreeSet
118+ * @see ArrayList
119+ * @see LinkedList
120+ * @see Vector
121+ * @see Collections
122+ * @see Arrays
123+ * @see AbstractCollection
124+ * @since 1.2
125+ */
126+
127+public interface Collection<E> extends Iterable<E> {
128+ // Query Operations
129+
130+ /**
131+ * Returns the number of elements in this collection. If this collection
132+ * contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
133+ * <tt>Integer.MAX_VALUE</tt>.
134+ *
135+ * @return the number of elements in this collection
136+ */
137+ int size();
138+
139+ /**
140+ * Returns <tt>true</tt> if this collection contains no elements.
141+ *
142+ * @return <tt>true</tt> if this collection contains no elements
143+ */
144+ boolean isEmpty();
145+
146+ /**
147+ * Returns <tt>true</tt> if this collection contains the specified element.
148+ * More formally, returns <tt>true</tt> if and only if this collection
149+ * contains at least one element <tt>e</tt> such that
150+ * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
151+ *
152+ * @param o element whose presence in this collection is to be tested
153+ * @return <tt>true</tt> if this collection contains the specified
154+ * element
155+ * @throws ClassCastException if the type of the specified element
156+ * is incompatible with this collection
157+ * (<a href="#optional-restrictions">optional</a>)
158+ * @throws NullPointerException if the specified element is null and this
159+ * collection does not permit null elements
160+ * (<a href="#optional-restrictions">optional</a>)
161+ */
162+ boolean contains(Object o);
163+
164+ /**
165+ * Returns an iterator over the elements in this collection. There are no
166+ * guarantees concerning the order in which the elements are returned
167+ * (unless this collection is an instance of some class that provides a
168+ * guarantee).
169+ *
170+ * @return an <tt>Iterator</tt> over the elements in this collection
171+ */
172+ Iterator<E> iterator();
173+
174+ /**
175+ * Returns an array containing all of the elements in this collection.
176+ * If this collection makes any guarantees as to what order its elements
177+ * are returned by its iterator, this method must return the elements in
178+ * the same order.
179+ *
180+ * <p>The returned array will be "safe" in that no references to it are
181+ * maintained by this collection. (In other words, this method must
182+ * allocate a new array even if this collection is backed by an array).
183+ * The caller is thus free to modify the returned array.
184+ *
185+ * <p>This method acts as bridge between array-based and collection-based
186+ * APIs.
187+ *
188+ * @return an array containing all of the elements in this collection
189+ */
190+ Object[] toArray();
191+
192+ /**
193+ * Returns an array containing all of the elements in this collection;
194+ * the runtime type of the returned array is that of the specified array.
195+ * If the collection fits in the specified array, it is returned therein.
196+ * Otherwise, a new array is allocated with the runtime type of the
197+ * specified array and the size of this collection.
198+ *
199+ * <p>If this collection fits in the specified array with room to spare
200+ * (i.e., the array has more elements than this collection), the element
201+ * in the array immediately following the end of the collection is set to
202+ * <tt>null</tt>. (This is useful in determining the length of this
203+ * collection <i>only</i> if the caller knows that this collection does
204+ * not contain any <tt>null</tt> elements.)
205+ *
206+ * <p>If this collection makes any guarantees as to what order its elements
207+ * are returned by its iterator, this method must return the elements in
208+ * the same order.
209+ *
210+ * <p>Like the {@link #toArray()} method, this method acts as bridge between
211+ * array-based and collection-based APIs. Further, this method allows
212+ * precise control over the runtime type of the output array, and may,
213+ * under certain circumstances, be used to save allocation costs.
214+ *
215+ * <p>Suppose <tt>x</tt> is a collection known to contain only strings.
216+ * The following code can be used to dump the collection into a newly
217+ * allocated array of <tt>String</tt>:
218+ *
219+ * <pre>
220+ * String[] y = x.toArray(new String[0]);</pre>
221+ *
222+ * Note that <tt>toArray(new Object[0])</tt> is identical in function to
223+ * <tt>toArray()</tt>.
224+ *
225+ * @param a the array into which the elements of this collection are to be
226+ * stored, if it is big enough; otherwise, a new array of the same
227+ * runtime type is allocated for this purpose.
228+ * @return an array containing all of the elements in this collection
229+ * @throws ArrayStoreException if the runtime type of the specified array
230+ * is not a supertype of the runtime type of every element in
231+ * this collection
232+ * @throws NullPointerException if the specified array is null
233+ */
234+ <T> T[] toArray(T[] a);
235+
236+ // Modification Operations
237+
238+ /**
239+ * Ensures that this collection contains the specified element (optional
240+ * operation). Returns <tt>true</tt> if this collection changed as a
241+ * result of the call. (Returns <tt>false</tt> if this collection does
242+ * not permit duplicates and already contains the specified element.)<p>
243+ *
244+ * Collections that support this operation may place limitations on what
245+ * elements may be added to this collection. In particular, some
246+ * collections will refuse to add <tt>null</tt> elements, and others will
247+ * impose restrictions on the type of elements that may be added.
248+ * Collection classes should clearly specify in their documentation any
249+ * restrictions on what elements may be added.<p>
250+ *
251+ * If a collection refuses to add a particular element for any reason
252+ * other than that it already contains the element, it <i>must</i> throw
253+ * an exception (rather than returning <tt>false</tt>). This preserves
254+ * the invariant that a collection always contains the specified element
255+ * after this call returns.
256+ *
257+ * @param e element whose presence in this collection is to be ensured
258+ * @return <tt>true</tt> if this collection changed as a result of the
259+ * call
260+ * @throws UnsupportedOperationException if the <tt>add</tt> operation
261+ * is not supported by this collection
262+ * @throws ClassCastException if the class of the specified element
263+ * prevents it from being added to this collection
264+ * @throws NullPointerException if the specified element is null and this
265+ * collection does not permit null elements
266+ * @throws IllegalArgumentException if some property of the element
267+ * prevents it from being added to this collection
268+ * @throws IllegalStateException if the element cannot be added at this
269+ * time due to insertion restrictions
270+ */
271+ boolean add(E e);
272+
273+ /**
274+ * Removes a single instance of the specified element from this
275+ * collection, if it is present (optional operation). More formally,
276+ * removes an element <tt>e</tt> such that
277+ * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>, if
278+ * this collection contains one or more such elements. Returns
279+ * <tt>true</tt> if this collection contained the specified element (or
280+ * equivalently, if this collection changed as a result of the call).
281+ *
282+ * @param o element to be removed from this collection, if present
283+ * @return <tt>true</tt> if an element was removed as a result of this call
284+ * @throws ClassCastException if the type of the specified element
285+ * is incompatible with this collection
286+ * (<a href="#optional-restrictions">optional</a>)
287+ * @throws NullPointerException if the specified element is null and this
288+ * collection does not permit null elements
289+ * (<a href="#optional-restrictions">optional</a>)
290+ * @throws UnsupportedOperationException if the <tt>remove</tt> operation
291+ * is not supported by this collection
292+ */
293+ boolean remove(Object o);
294+
295+
296+ // Bulk Operations
297+
298+ /**
299+ * Returns <tt>true</tt> if this collection contains all of the elements
300+ * in the specified collection.
301+ *
302+ * @param c collection to be checked for containment in this collection
303+ * @return <tt>true</tt> if this collection contains all of the elements
304+ * in the specified collection
305+ * @throws ClassCastException if the types of one or more elements
306+ * in the specified collection are incompatible with this
307+ * collection
308+ * (<a href="#optional-restrictions">optional</a>)
309+ * @throws NullPointerException if the specified collection contains one
310+ * or more null elements and this collection does not permit null
311+ * elements
312+ * (<a href="#optional-restrictions">optional</a>),
313+ * or if the specified collection is null.
314+ * @see #contains(Object)
315+ */
316+ boolean containsAll(Collection<?> c);
317+
318+ /**
319+ * Adds all of the elements in the specified collection to this collection
320+ * (optional operation). The behavior of this operation is undefined if
321+ * the specified collection is modified while the operation is in progress.
322+ * (This implies that the behavior of this call is undefined if the
323+ * specified collection is this collection, and this collection is
324+ * nonempty.)
325+ *
326+ * @param c collection containing elements to be added to this collection
327+ * @return <tt>true</tt> if this collection changed as a result of the call
328+ * @throws UnsupportedOperationException if the <tt>addAll</tt> operation
329+ * is not supported by this collection
330+ * @throws ClassCastException if the class of an element of the specified
331+ * collection prevents it from being added to this collection
332+ * @throws NullPointerException if the specified collection contains a
333+ * null element and this collection does not permit null elements,
334+ * or if the specified collection is null
335+ * @throws IllegalArgumentException if some property of an element of the
336+ * specified collection prevents it from being added to this
337+ * collection
338+ * @throws IllegalStateException if not all the elements can be added at
339+ * this time due to insertion restrictions
340+ * @see #add(Object)
341+ */
342+ boolean addAll(Collection<? extends E> c);
343+
344+ /**
345+ * Removes all of this collection's elements that are also contained in the
346+ * specified collection (optional operation). After this call returns,
347+ * this collection will contain no elements in common with the specified
348+ * collection.
349+ *
350+ * @param c collection containing elements to be removed from this collection
351+ * @return <tt>true</tt> if this collection changed as a result of the
352+ * call
353+ * @throws UnsupportedOperationException if the <tt>removeAll</tt> method
354+ * is not supported by this collection
355+ * @throws ClassCastException if the types of one or more elements
356+ * in this collection are incompatible with the specified
357+ * collection
358+ * (<a href="#optional-restrictions">optional</a>)
359+ * @throws NullPointerException if this collection contains one or more
360+ * null elements and the specified collection does not support
361+ * null elements
362+ * (<a href="#optional-restrictions">optional</a>),
363+ * or if the specified collection is null
364+ * @see #remove(Object)
365+ * @see #contains(Object)
366+ */
367+ boolean removeAll(Collection<?> c);
368+
369+ /**
370+ * Retains only the elements in this collection that are contained in the
371+ * specified collection (optional operation). In other words, removes from
372+ * this collection all of its elements that are not contained in the
373+ * specified collection.
374+ *
375+ * @param c collection containing elements to be retained in this collection
376+ * @return <tt>true</tt> if this collection changed as a result of the call
377+ * @throws UnsupportedOperationException if the <tt>retainAll</tt> operation
378+ * is not supported by this collection
379+ * @throws ClassCastException if the types of one or more elements
380+ * in this collection are incompatible with the specified
381+ * collection
382+ * (<a href="#optional-restrictions">optional</a>)
383+ * @throws NullPointerException if this collection contains one or more
384+ * null elements and the specified collection does not permit null
385+ * elements
386+ * (<a href="#optional-restrictions">optional</a>),
387+ * or if the specified collection is null
388+ * @see #remove(Object)
389+ * @see #contains(Object)
390+ */
391+ boolean retainAll(Collection<?> c);
392+
393+ /**
394+ * Removes all of the elements from this collection (optional operation).
395+ * The collection will be empty after this method returns.
396+ *
397+ * @throws UnsupportedOperationException if the <tt>clear</tt> operation
398+ * is not supported by this collection
399+ */
400+ void clear();
401+
402+
403+ // Comparison and hashing
404+
405+ /**
406+ * Compares the specified object with this collection for equality. <p>
407+ *
408+ * While the <tt>Collection</tt> interface adds no stipulations to the
409+ * general contract for the <tt>Object.equals</tt>, programmers who
410+ * implement the <tt>Collection</tt> interface "directly" (in other words,
411+ * create a class that is a <tt>Collection</tt> but is not a <tt>Set</tt>
412+ * or a <tt>List</tt>) must exercise care if they choose to override the
413+ * <tt>Object.equals</tt>. It is not necessary to do so, and the simplest
414+ * course of action is to rely on <tt>Object</tt>'s implementation, but
415+ * the implementor may wish to implement a "value comparison" in place of
416+ * the default "reference comparison." (The <tt>List</tt> and
417+ * <tt>Set</tt> interfaces mandate such value comparisons.)<p>
418+ *
419+ * The general contract for the <tt>Object.equals</tt> method states that
420+ * equals must be symmetric (in other words, <tt>a.equals(b)</tt> if and
421+ * only if <tt>b.equals(a)</tt>). The contracts for <tt>List.equals</tt>
422+ * and <tt>Set.equals</tt> state that lists are only equal to other lists,
423+ * and sets to other sets. Thus, a custom <tt>equals</tt> method for a
424+ * collection class that implements neither the <tt>List</tt> nor
425+ * <tt>Set</tt> interface must return <tt>false</tt> when this collection
426+ * is compared to any list or set. (By the same logic, it is not possible
427+ * to write a class that correctly implements both the <tt>Set</tt> and
428+ * <tt>List</tt> interfaces.)
429+ *
430+ * @param o object to be compared for equality with this collection
431+ * @return <tt>true</tt> if the specified object is equal to this
432+ * collection
433+ *
434+ * @see Object#equals(Object)
435+ * @see Set#equals(Object)
436+ * @see List#equals(Object)
437+ */
438+ boolean equals(Object o);
439+
440+ /**
441+ * Returns the hash code value for this collection. While the
442+ * <tt>Collection</tt> interface adds no stipulations to the general
443+ * contract for the <tt>Object.hashCode</tt> method, programmers should
444+ * take note that any class that overrides the <tt>Object.equals</tt>
445+ * method must also override the <tt>Object.hashCode</tt> method in order
446+ * to satisfy the general contract for the <tt>Object.hashCode</tt> method.
447+ * In particular, <tt>c1.equals(c2)</tt> implies that
448+ * <tt>c1.hashCode()==c2.hashCode()</tt>.
449+ *
450+ * @return the hash code value for this collection
451+ *
452+ * @see Object#hashCode()
453+ * @see Object#equals(Object)
454+ */
455+ int hashCode();
456+}