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Java > Open Source Codes > org > springframework > core > Ordered


1 /*
2  * Copyright 2002-2006 the original author or authors.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.springframework.core;
18
19 /**
20  * Interface that can be implemented by objects that should be
21  * orderable, for example in a Collection.
22  *
23  * <p>The actual order can be interpreted as prioritization, with
24  * the first object (with the lowest order value) having the highest
25  * priority.
26  *
27  * @author Juergen Hoeller
28  * @since 07.04.2003
29  * @see OrderComparator
30  * @see org.springframework.core.annotation.Order
31  */
32 public interface Ordered {
33
34     /**
35      * Useful constant for the highest precedence value.
36      * @see java.lang.Integer#MIN_VALUE
37      */
38     int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;
39
40     /**
41      * Useful constant for the lowest precedence value.
42      * @see java.lang.Integer#MAX_VALUE
43      */
44     int LOWEST_PRECEDENCE = Integer.MAX_VALUE;
45
46
47     /**
48      * Return the order value of this object, with a
49      * higher value meaning greater in terms of sorting.
50      * <p>Normally starting with 0 or 1, with {@link #LOWEST_PRECEDENCE}
51      * indicating greatest. Same order values will result in arbitrary
52      * positions for the affected objects.
53      * <p>Higher value can be interpreted as lower priority,
54      * consequently the first object has highest priority
55      * (somewhat analogous to Servlet "load-on-startup" values).
56      * <p>Note that order values below 0 are reserved for framework
57      * purposes. Application-specified values should always be 0 or
58      * greater, with only framework components (internal or third-party)
59      * supposed to use lower values.
60      * @return the order value
61      * @see #LOWEST_PRECEDENCE
62      */
63     int getOrder();
64
65 }
66
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