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Java > Open Source Codes > jegg > impl > Priority


1 /*
2  * Copyright (c) 2004, Bruce Lowery
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions are met:
7  *
8  * - Redistributions of source code must retain the above copyright notice,
9  * this list of conditions and the following disclaimer.
10  * - Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * - Neither the name of JEGG nor the names of its contributors may be used
14  * to endorse or promote products derived from this software without
15  * specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
21  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27  * POSSIBILITY OF SUCH DAMAGE.
28  */
29 package jegg.impl;
30
31 /**
32  * Enumeration of the dispatch priorities that may be assigned to
33  * a message being sent from one egg to another. Queued messages with a higher
34  * priority are dispatched ahead of lower priority messages.
35  */
36 public final class Priority implements Comparable JavaDoc
37 {
38     /** The highest dispatch priority */
39     public static final Priority HIGH = new Priority(10);
40     /** The normal dispatch priority */
41     public static final Priority MEDIUM = new Priority(5);
42     /** The lowest dispatch priority */
43     public static final Priority LOW = new Priority(1);
44     
45     /** The numeric value of this priority */
46     private int level = 0;
47     
48     /**
49      * Construct a dispatch priority.
50      * @param lvl the value to assign the new priority (the higher the value, the
51      * higher the priority).
52      */
53     private Priority(int lvl)
54     {
55         level = lvl;
56     }
57     
58     /**
59      * Implementation of the {@link java.lang.Comparable Comparable} interface
60      * that that priorities will be properly handled by a sorted set.
61      */
62     public int compareTo(Object JavaDoc o)
63     {
64         if (!(o instanceof Priority))
65         {
66             throw new IllegalArgumentException JavaDoc("not a Priority instance");
67         }
68         Priority p = (Priority) o;
69         return p.level - level;
70     }
71 }
72
73
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