01: // ============================================================================
02: // $Id: ChainedComparator.java,v 1.4 2005/08/02 23:45:22 davidahall Exp $
03: // Copyright (c) 2003-2005 David A. Hall
04: // ============================================================================
05: // The contents of this file are subject to the Common Development and
06: // Distribution License (CDDL), Version 1.0 (the License); you may not use this
07: // file except in compliance with the License. You should have received a copy
08: // of the the License along with this file: if not, a copy of the License is
09: // 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.util;
33:
34: import java.io.Serializable;
35: import java.util.Comparator;
36:
37: // UNTESTED
38:
39: /**
40: * Comparator wrapper that uses a pair of comparators internally. The primary
41: * comparator is evaluated first, and if it returns 0 (equal), then this returns
42: * the result of the secondary comparator.
43: *
44: * @author <a href="mailto:davidahall@users.sf.net">David A. Hall</a>
45: */
46:
47: public class ChainedComparator<T> implements Comparator<T>,
48: Serializable {
49: static final long serialVersionUID = -8015644817201268699L;
50:
51: private Comparator<T> _primary;
52: private Comparator<T> _secondary;
53:
54: public ChainedComparator(Comparator<T> primary,
55: Comparator<T> secondary) {
56: if (primary == null || secondary == null) {
57: String msg = "Two Comparators are required: at least one was null";
58: throw new IllegalArgumentException(msg);
59: }
60:
61: _primary = primary;
62: _secondary = secondary;
63: }
64:
65: public int compare(T x, T y) {
66: int result = _primary.compare(x, y);
67: return (result == 0) ? _secondary.compare(x, y) : result;
68: }
69: }
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