KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > net > sf > jga > fn > algorithm > MinValue


1 // ============================================================================
2
// $Id: MinValue.java,v 1.8 2006/01/08 00:52:25 davidahall Exp $
3
// Copyright (c) 2003-2005 David A. Hall
4
// ============================================================================
5
// The contents of this file are subject to the Common Development and
6
// Distribution License (CDDL), Version 1.0 (the License); you may not use this
7
// file except in compliance with the License. You should have received a copy
8
// of the the License along with this file: if not, a copy of the License is
9
// available from Sun Microsystems, Inc.
10
//
11
// http://www.sun.com/cddl/cddl.html
12
//
13
// From time to time, the license steward (initially Sun Microsystems, Inc.) may
14
// publish revised and/or new versions of the License. You may not use,
15
// distribute, or otherwise make this file available under subsequent versions
16
// of the License.
17
//
18
// Alternatively, the contents of this file may be used under the terms of the
19
// GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
20
// case the provisions of the LGPL are applicable instead of those above. If you
21
// wish to allow use of your version of this file only under the terms of the
22
// LGPL, and not to allow others to use your version of this file under the
23
// terms of the CDDL, indicate your decision by deleting the provisions above
24
// and replace them with the notice and other provisions required by the LGPL.
25
// If you do not delete the provisions above, a recipient may use your version
26
// of this file under the terms of either the CDDL or the LGPL.
27
//
28
// This library is distributed in the hope that it will be useful,
29
// but WITHOUT ANY WARRANTY; without even the implied warranty of
30
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
31
// ============================================================================
32
package net.sf.jga.fn.algorithm;
33
34 import java.util.Collection JavaDoc;
35 import java.util.Collections JavaDoc;
36 import java.util.Comparator JavaDoc;
37 import net.sf.jga.fn.BinaryFunctor;
38 import net.sf.jga.fn.UnaryFunctor;
39
40 /**
41  * Identifies the smallest value in a collection.
42  * <p>
43  * To serialize a MinValue, the comparator passed at construction must be
44  * Serializable.
45  * <p>
46  * Copyright &copy; 2003-2005 David A. Hall
47  *
48  * @author <a HREF="mailto:davidahall@users.sf.net">David A. Hall</a>
49  */

50
51 public class MinValue<T> extends UnaryFunctor<Collection JavaDoc<? extends T>, T> {
52     
53     static final long serialVersionUID = 8518667936731775433L;
54
55     private Comparator JavaDoc<T> _comp;
56
57     /**
58      * Builds a MinValue functor that will use the given comparator to
59      * compare elements in the collection. Typically, the functor would compare
60      * its two arguments and return the lesser value.
61      * @throws IllegalArgumentException if the Comparator is null
62      */

63     public MinValue(Comparator JavaDoc<T> comp) {
64         if (comp == null)
65             throw new IllegalArgumentException JavaDoc();
66         
67         _comp = comp;
68     }
69
70     /**
71      * Returns the functor used to order values in the collection.
72      */

73     public Comparator JavaDoc<T> getComparator() {
74         return _comp;
75     }
76
77     /**
78      * Return the smallest value in the collection
79      * @throws NoSuchElementException if the collection is empty
80      */

81     public T fn(Collection JavaDoc<? extends T> collection) {
82         return Collections.min(collection, _comp);
83     }
84     
85     /**
86      * Calls the Visitor's <code>visit(MinValue)</code> method, if it
87      * implements the nested Visitor interface.
88      */

89     public void accept(net.sf.jga.fn.Visitor v) {
90         if (v instanceof MinValue.Visitor)
91             ((MinValue.Visitor)v).visit(this);
92         else
93             v.visit(this);
94     }
95
96     // Object overrides
97

98     public String JavaDoc toString() {
99         return "MinValue";
100     }
101     
102     // AcyclicVisitor
103

104     /**
105      * Interface for classes that may interpret an <b>MinValue</b> functor.
106      */

107     public interface Visitor extends net.sf.jga.fn.Visitor {
108         public void visit(MinValue host);
109     }
110 }
111
Popular Tags