KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > net > sf > jga > fn > comparison > NotEqualTo


1 // ============================================================================
2
// $Id: NotEqualTo.java,v 1.12 2006/01/08 00:52:25 davidahall Exp $
3
// Copyright (c) 2002-2005 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

33 package net.sf.jga.fn.comparison;
34
35 import net.sf.jga.fn.BinaryPredicate;
36 import java.util.Comparator JavaDoc;
37
38 /**
39  * Binary Predicate that returns TRUE for object arguments <b>x</b> and
40  * <b>y</b> when x != y using the built-in equals() method or an optional
41  * Comparator given at construction. By default, this object will not throw
42  * NullPointerException: it will return true if either runtime arguments is null
43  * but false if both are null. If an optional comparator is used, then its
44  * implementation will determine if a NullPointerException is thrown when passed
45  * a null argument.
46  * <p>
47  * To serialize an NotEqual functor, the comparator passed at construction(if
48  * any) must be Serializable.
49  * <p>
50  * Copyright &copy; 2002-2005 David A. Hall
51  *
52  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
53  **/

54
55
56 public class NotEqualTo<T> extends BinaryPredicate<T,T> {
57     
58     static final long serialVersionUID = 1892296018875494847L;
59
60     // An optional comparator used to compare values
61
Comparator JavaDoc<? super T> _comp;
62
63     /**
64      * Builds an EqualTo that uses the built-in equals method.
65      */

66     public NotEqualTo() {}
67     
68     /**
69      * Builds an EqualTo that uses the given comparator.
70      */

71     public NotEqualTo(Comparator JavaDoc<? super T> comp) {
72         _comp = comp;
73     }
74     
75     /**
76      * Returns the comparator in use by this functor, if any.
77      * @return the comparator in use by this functor, if any.
78      */

79     public Comparator JavaDoc<? super T> getComparator() { return _comp; }
80     
81     // BinaryPredicate interface
82

83     /**
84      * Given arguments <b>x</b> and <b>y</b>, returns !(x.equals(y)). Will not
85      * throw NullPointerException if either x or y are null: will return true
86      * if either x or y (but not both) are null, will return false if both x
87      * and y are null.
88      *
89      * @return !(x.equals(y))
90      */

91     public Boolean JavaDoc fn(T x, T y) {
92         if (_comp == null)
93             return (x == null) ? y != null :
94                    (y == null) ? true : ! (x.equals(y));
95         else
96             return _comp.compare(x, y) != 0;
97     }
98
99     /**
100      * Calls the Visitor's <code>visit(NotEqualTo)</code> method, if it
101      * implements the nested Visitor interface.
102      */

103     public void accept(net.sf.jga.fn.Visitor v) {
104         if (v instanceof NotEqualTo.Visitor)
105             ((NotEqualTo.Visitor)v).visit(this);
106         else
107             v.visit(this);
108     }
109
110     // Object overrides
111

112     public String JavaDoc toString() {
113         return "NotEqualTo";
114     }
115     
116     // Acyclic Visitor
117

118     /**
119      * Interface for classes that may interpret a <b>NotEqualTo</b> predicate.
120      */

121     public interface Visitor extends net.sf.jga.fn.Visitor {
122         public void visit(NotEqualTo host);
123     }
124 }
125
Popular Tags