001: // ============================================================================
002: // $Id: NotEqualTo.java,v 1.12 2006/01/08 00:52:25 davidahall Exp $
003: // Copyright (c) 2002-2005 David A. Hall
004: // ============================================================================
005: // The contents of this file are subject to the Common Development and
006: // Distribution License (CDDL), Version 1.0 (the License); you may not use this
007: // file except in compliance with the License. You should have received a copy
008: // of the the License along with this file: if not, a copy of the License is
009: // available from Sun Microsystems, Inc.
010: //
011: // http://www.sun.com/cddl/cddl.html
012: //
013: // From time to time, the license steward (initially Sun Microsystems, Inc.) may
014: // publish revised and/or new versions of the License. You may not use,
015: // distribute, or otherwise make this file available under subsequent versions
016: // of the License.
017: //
018: // Alternatively, the contents of this file may be used under the terms of the
019: // GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
020: // case the provisions of the LGPL are applicable instead of those above. If you
021: // wish to allow use of your version of this file only under the terms of the
022: // LGPL, and not to allow others to use your version of this file under the
023: // terms of the CDDL, indicate your decision by deleting the provisions above
024: // and replace them with the notice and other provisions required by the LGPL.
025: // If you do not delete the provisions above, a recipient may use your version
026: // of this file under the terms of either the CDDL or the LGPL.
027: //
028: // This library is distributed in the hope that it will be useful,
029: // but WITHOUT ANY WARRANTY; without even the implied warranty of
030: // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
031: // ============================================================================
032:
033: package net.sf.jga.fn.comparison;
034:
035: import net.sf.jga.fn.BinaryPredicate;
036: import java.util.Comparator;
037:
038: /**
039: * Binary Predicate that returns TRUE for object arguments <b>x</b> and
040: * <b>y</b> when x != y using the built-in equals() method or an optional
041: * Comparator given at construction. By default, this object will not throw
042: * NullPointerException: it will return true if either runtime arguments is null
043: * but false if both are null. If an optional comparator is used, then its
044: * implementation will determine if a NullPointerException is thrown when passed
045: * a null argument.
046: * <p>
047: * To serialize an NotEqual functor, the comparator passed at construction(if
048: * any) must be Serializable.
049: * <p>
050: * Copyright © 2002-2005 David A. Hall
051: *
052: * @author <a href="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
053: **/
054:
055: public class NotEqualTo<T> extends BinaryPredicate<T, T> {
056:
057: static final long serialVersionUID = 1892296018875494847L;
058:
059: // An optional comparator used to compare values
060: Comparator<? super T> _comp;
061:
062: /**
063: * Builds an EqualTo that uses the built-in equals method.
064: */
065: public NotEqualTo() {
066: }
067:
068: /**
069: * Builds an EqualTo that uses the given comparator.
070: */
071: public NotEqualTo(Comparator<? super T> comp) {
072: _comp = comp;
073: }
074:
075: /**
076: * Returns the comparator in use by this functor, if any.
077: * @return the comparator in use by this functor, if any.
078: */
079: public Comparator<? super T> getComparator() {
080: return _comp;
081: }
082:
083: // BinaryPredicate interface
084:
085: /**
086: * Given arguments <b>x</b> and <b>y</b>, returns !(x.equals(y)). Will not
087: * throw NullPointerException if either x or y are null: will return true
088: * if either x or y (but not both) are null, will return false if both x
089: * and y are null.
090: *
091: * @return !(x.equals(y))
092: */
093: public Boolean fn(T x, T y) {
094: if (_comp == null)
095: return (x == null) ? y != null : (y == null) ? true : !(x
096: .equals(y));
097: else
098: return _comp.compare(x, y) != 0;
099: }
100:
101: /**
102: * Calls the Visitor's <code>visit(NotEqualTo)</code> method, if it
103: * implements the nested Visitor interface.
104: */
105: public void accept(net.sf.jga.fn.Visitor v) {
106: if (v instanceof NotEqualTo.Visitor)
107: ((NotEqualTo.Visitor) v).visit(this );
108: else
109: v.visit(this );
110: }
111:
112: // Object overrides
113:
114: public String toString() {
115: return "NotEqualTo";
116: }
117:
118: // Acyclic Visitor
119:
120: /**
121: * Interface for classes that may interpret a <b>NotEqualTo</b> predicate.
122: */
123: public interface Visitor extends net.sf.jga.fn.Visitor {
124: public void visit(NotEqualTo host);
125: }
126: }
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