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Java > Open Source Codes > net > sf > jasperreports > engine > util > Pair


1 /*
2  * ============================================================================
3  * GNU Lesser General Public License
4  * ============================================================================
5  *
6  * JasperReports - Free Java report-generating library.
7  * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
8  *
9  * This library is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22  *
23  * JasperSoft Corporation
24  * 303 Second Street, Suite 450 North
25  * San Francisco, CA 94107
26  * http://www.jaspersoft.com
27  */
28 package net.sf.jasperreports.engine.util;
29
30 import java.io.Serializable JavaDoc;
31
32
33 /**
34  * Utility class used to pair two objects.
35  *
36  * @author Lucian Chirita (lucianc@users.sourceforge.net)
37  * @version $Id: Pair.java 1364 2006-08-31 18:13:20 +0300 (Thu, 31 Aug 2006) lucianc $
38  */
39 public class Pair implements Serializable JavaDoc
40 {
41     private static final long serialVersionUID = 1L;
42     
43     private final Object JavaDoc o1;
44     private final Object JavaDoc o2;
45     private final int hash;
46
47     
48     /**
49      * Create a pair instance.
50      *
51      * @param o1 the first member of the pair
52      * @param o2 the second member of the pair
53      */
54     public Pair(Object JavaDoc o1, Object JavaDoc o2)
55     {
56         this.o1 = o1;
57         this.o2 = o2;
58         this.hash = computeHash();
59     }
60
61     private int computeHash()
62     {
63         int hashCode = o1 == null ? 0 : o1.hashCode();
64         hashCode *= 31;
65         hashCode += o2 == null ? 0 : o2.hashCode();
66         return hashCode;
67     }
68
69     public boolean equals(Object JavaDoc o)
70     {
71         if (o == this)
72         {
73             return true;
74         }
75         
76         if (o == null || !(o instanceof Pair))
77         {
78             return false;
79         }
80         
81         Pair p = (Pair) o;
82         
83         return (p.o1 == null ? o1 == null : (o1 != null && p.o1.equals(o1))) &&
84             (p.o2 == null ? o2 == null : (o2 != null && p.o2.equals(o2)));
85     }
86
87     public int hashCode()
88     {
89         return hash;
90     }
91     
92     public String JavaDoc toString()
93     {
94         return "(" + String.valueOf(o1) + ", " + String.valueOf(o2) + ")";
95     }
96
97 }
98
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