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Java > Open Source Codes > org > jgrapht > ext > IntegerNameProvider


1 /* ==========================================
2  * JGraphT : a free Java graph-theory library
3  * ==========================================
4  *
5  * Project Info: http://jgrapht.sourceforge.net/
6  * Project Creator: Barak Naveh (http://sourceforge.net/users/barak_naveh)
7  *
8  * (C) Copyright 2003-2006, by Barak Naveh and Contributors.
9  *
10  * This library is free software; you can redistribute it and/or modify it
11  * under the terms of the GNU Lesser General Public License as published by
12  * the Free Software Foundation; either version 2.1 of the License, or
13  * (at your option) any later version.
14  *
15  * This library is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
17  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
18  * License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public License
21  * along with this library; if not, write to the Free Software Foundation,
22  * Inc.,
23  * 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
24  */
25 /* ------------------
26  * IntegerNameProvider.java
27  * ------------------
28  * (C) Copyright 2005-2006, by Charles Fry and Contributors.
29  *
30  * Original Author: Charles Fry
31  *
32  * $Id: IntegerNameProvider.java 504 2006-07-03 02:37:26Z perfecthash $
33  *
34  * Changes
35  * -------
36  * 13-Dec-2005 : Initial Version (CF);
37  *
38  */
39 package org.jgrapht.ext;
40
41 import java.util.*;
42
43 import org.jgrapht.event.*;
44
45
46 /**
47  * Assigns a unique integer to represent each vertex. Each instance of
48  * IntegerNameProvider maintains an internal map between every vertex it has
49  * ever seen and the unique integer representing that vertex. As a result it is
50  * probably desirable to have a separate instance for each distinct graph.
51  *
52  * @author Charles Fry
53  */
54 public class IntegerNameProvider<V>
55     implements VertexNameProvider<V>
56 {
57
58     //~ Instance fields -------------------------------------------------------
59
60     private int nextID = 1;
61     private final Map<V, Integer JavaDoc> idMap = new HashMap<V, Integer JavaDoc>();
62
63     //~ Methods ---------------------------------------------------------------
64
65     /**
66      * Clears all cached identifiers, and resets the unique identifier counter.
67      */
68     public void clear()
69     {
70         nextID = 1;
71         idMap.clear();
72     }
73
74     /**
75      * Returns the String representation of the unique integer representing a
76      * vertex.
77      *
78      * @param vertex the vertex to be named
79      *
80      * @return the name of
81      *
82      * @see GraphListener#edgeAdded(GraphEdgeChangeEvent)
83      */
84     public String JavaDoc getVertexName(V vertex)
85     {
86         Integer JavaDoc id = idMap.get(vertex);
87         if (id == null) {
88             id = nextID++;
89             idMap.put(vertex, id);
90         }
91
92         return id.toString();
93     }
94 }
95
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