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root/jsr166/jsr166/src/main/java/util/Stack.java

Comparing jsr166/src/main/java/util/Stack.java (file contents):
Revision 1.2 by jsr166, Sat Oct 1 21:43:43 2005 UTC vs.
Revision 1.9 by jsr166, Sun Sep 5 21:32:19 2010 UTC

#	Line 1 | Line 1
1		/*
2	<	* %W% %E%
2	>	* Copyright (c) 1994, 2005, Oracle and/or its affiliates. All rights reserved.
3	>	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4		*
5	<	* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
6	<	* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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.  Sun designates this
8	>	* particular file as subject to the "Classpath" exception as provided
9	>	* by Sun 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 <code>Stack</code> class represents a last-in-first-out
30	<	* (LIFO) stack of objects. It extends class <tt>Vector</tt> with five
31	<	* operations that allow a vector to be treated as a stack. The usual
29	>	* The <code>Stack</code> class represents a last-in-first-out
30	>	* (LIFO) stack of objects. It extends class <tt>Vector</tt> with five
31	>	* operations that allow a vector to be treated as a stack. The usual
32		* <tt>push</tt> and <tt>pop</tt> operations are provided, as well as a
33	<	* method to <tt>peek</tt> at the top item on the stack, a method to test
34	<	* for whether the stack is <tt>empty</tt>, and a method to <tt>search</tt>
33	>	* method to <tt>peek</tt> at the top item on the stack, a method to test
34	>	* for whether the stack is <tt>empty</tt>, and a method to <tt>search</tt>
35		* the stack for an item and discover how far it is from the top.
36		* <p>
37	<	* When a stack is first created, it contains no items.
37	>	* When a stack is first created, it contains no items.
38		*
39	<	* <p>A more complete and consistent set of LIFO stack operations are
40	<	* available in {@link Deque} interface and its implementations, which
39	>	* <p>A more complete and consistent set of LIFO stack operations is
40	>	* provided by the {@link Deque} interface and its implementations, which
41		* should be used in preference to this class.  For example:
42	<	* <pre>
43	<	*   Deque&lt;Integer&gt; stack = new ArrayDeque&lt;Integer&gt();
26	<	* </pre>
42	>	* <pre>   {@code
43	>	*   Deque<Integer> stack = new ArrayDeque<Integer>();}</pre>
44		*
45		* @author  Jonathan Payne
29	–	* @version %I%, %G%
46		* @since   JDK1.0
47		*/
48		public
#	Line 38 | Line 54 | class Stack<E> extends Vector<E> {
54		}
55
56		/**
57	<	* Pushes an item onto the top of this stack. This has exactly
57	>	* Pushes an item onto the top of this stack. This has exactly
58		* the same effect as:
59		* <blockquote><pre>
60		* addElement(item)</pre></blockquote>
#	Line 48 | Line 64 | class Stack<E> extends Vector<E> {
64		* @see     java.util.Vector#addElement
65		*/
66		public E push(E item) {
67	<	addElement(item);
67	>	addElement(item);
68
69	<	return item;
69	>	return item;
70		}
71
72		/**
73	<	* Removes the object at the top of this stack and returns that
74	<	* object as the value of this function.
73	>	* Removes the object at the top of this stack and returns that
74	>	* object as the value of this function.
75		*
76	<	* @return     The object at the top of this stack (the last item
76	>	* @return     The object at the top of this stack (the last item
77		*             of the <tt>Vector</tt> object).
78		* @exception  EmptyStackException  if this stack is empty.
79		*/
80		public synchronized E pop() {
81	<	E       obj;
82	<	int     len = size();
81	>	E       obj;
82	>	int     len = size();
83
84	<	obj = peek();
85	<	removeElementAt(len - 1);
84	>	obj = peek();
85	>	removeElementAt(len - 1);
86
87	<	return obj;
87	>	return obj;
88		}
89
90		/**
91	<	* Looks at the object at the top of this stack without removing it
92	<	* from the stack.
91	>	* Looks at the object at the top of this stack without removing it
92	>	* from the stack.
93		*
94	<	* @return     the object at the top of this stack (the last item
95	<	*             of the <tt>Vector</tt> object).
94	>	* @return     the object at the top of this stack (the last item
95	>	*             of the <tt>Vector</tt> object).
96		* @exception  EmptyStackException  if this stack is empty.
97		*/
98		public synchronized E peek() {
99	<	int     len = size();
99	>	int     len = size();
100
101	<	if (len == 0)
102	<	throw new EmptyStackException();
103	<	return elementAt(len - 1);
101	>	if (len == 0)
102	>	throw new EmptyStackException();
103	>	return elementAt(len - 1);
104		}
105
106		/**
107		* Tests if this stack is empty.
108		*
109	<	* @return  <code>true</code> if and only if this stack contains
109	>	* @return  <code>true</code> if and only if this stack contains
110		*          no items; <code>false</code> otherwise.
111		*/
112		public boolean empty() {
113	<	return size() == 0;
113	>	return size() == 0;
114		}
115
116		/**
117	<	* Returns the 1-based position where an object is on this stack.
118	<	* If the object <tt>o</tt> occurs as an item in this stack, this
119	<	* method returns the distance from the top of the stack of the
120	<	* occurrence nearest the top of the stack; the topmost item on the
121	<	* stack is considered to be at distance <tt>1</tt>. The <tt>equals</tt>
122	<	* method is used to compare <tt>o</tt> to the
117	>	* Returns the 1-based position where an object is on this stack.
118	>	* If the object <tt>o</tt> occurs as an item in this stack, this
119	>	* method returns the distance from the top of the stack of the
120	>	* occurrence nearest the top of the stack; the topmost item on the
121	>	* stack is considered to be at distance <tt>1</tt>. The <tt>equals</tt>
122	>	* method is used to compare <tt>o</tt> to the
123		* items in this stack.
124		*
125		* @param   o   the desired object.
126	<	* @return  the 1-based position from the top of the stack where
126	>	* @return  the 1-based position from the top of the stack where
127		*          the object is located; the return value <code>-1</code>
128		*          indicates that the object is not on the stack.
129		*/
130		public synchronized int search(Object o) {
131	<	int i = lastIndexOf(o);
131	>	int i = lastIndexOf(o);
132
133	<	if (i >= 0) {
134	<	return size() - i;
135	<	}
136	<	return -1;
133	>	if (i >= 0) {
134	>	return size() - i;
135	>	}
136	>	return -1;
137		}
138
139		/** use serialVersionUID from JDK 1.0.2 for interoperability */

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