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Java > Open Source Codes > org > jgrapht > generate > RingGraphGenerator


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  * RingGraphGenerator.java
27  * -------------------
28  * (C) Copyright 2003-2006, by John V. Sichi and Contributors.
29  *
30  * Original Author: John V. Sichi
31  * Contributor(s): -
32  *
33  * $Id: RingGraphGenerator.java 504 2006-07-03 02:37:26Z perfecthash $
34  *
35  * Changes
36  * -------
37  * 16-Sep-2003 : Initial revision (JVS);
38  *
39  */

40 package org.jgrapht.generate;
41
42 import java.util.*;
43
44 import org.jgrapht.*;
45
46
47 /**
48  * Generates a ring graph of any size. A ring graph is a graph that contains a
49  * single cycle that passes through all its vertices exactly once. For a
50  * directed graph, the generated edges are oriented consistently around the
51  * ring.
52  *
53  * @author John V. Sichi
54  * @since Sep 16, 2003
55  */

56 public class RingGraphGenerator<V, E>
57     implements GraphGenerator<V, E, V>
58 {
59
60     //~ Instance fields -------------------------------------------------------
61

62     private int size;
63
64     //~ Constructors ----------------------------------------------------------
65

66     /**
67      * Construct a new RingGraphGenerator.
68      *
69      * @param size number of vertices to be generated
70      *
71      * @throws IllegalArgumentException if the specified size is negative.
72      */

73     public RingGraphGenerator(int size)
74     {
75         if (size < 0) {
76             throw new IllegalArgumentException JavaDoc("must be non-negative");
77         }
78
79         this.size = size;
80     }
81
82     //~ Methods ---------------------------------------------------------------
83

84     /**
85      * {@inheritDoc}
86      */

87     public void generateGraph(
88         Graph<V, E> target,
89         VertexFactory<V> vertexFactory,
90         Map<String JavaDoc, V> resultMap)
91     {
92         if (size < 1) {
93             return;
94         }
95
96         LinearGraphGenerator<V, E> linearGenerator =
97             new LinearGraphGenerator<V, E>(size);
98         Map<String JavaDoc, V> privateMap = new HashMap<String JavaDoc, V>();
99         linearGenerator.generateGraph(target, vertexFactory, privateMap);
100
101         V startVertex = privateMap.get(LinearGraphGenerator.START_VERTEX);
102         V endVertex = privateMap.get(LinearGraphGenerator.END_VERTEX);
103         target.addEdge(endVertex, startVertex);
104     }
105 }
106
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