Value


1   /*****************************************
2    *                                       *
3    *  JBoss Portal: The OpenSource Portal  *
4    *                                       *
5    *   Distributable under LGPL license.   *
6    *   See terms of license at gnu.org.    *
7    *                                       *
8    *****************************************/
9   package org.jboss.portal.common.value;
10  
11  
12  import java.io.Serializable  ;
13  import java.util.List  ;
14  
15  /**
16   * A read only interface used to retrieve data. It represents both for
17   * mono value and multi values. It must implement equals and hashCode.
18   *
19   * The semantics :
20   *
21   * |  Storage  | mono |   multi   |
22   * |       xxx |  xxx |     [xxx] |
23   * |      null | null |    [null] |
24   * --------------------------------
25   * |        [] | null |        [] |
26   * | [null,..] | null | [null,..] |
27   * |  ["1",..] |  "1" |  ["1",..] |
28   *
29   * @author <a HREF="mailto:julien@jboss.org">Julien Viet</a>
30   * @version $Revision: 1.2 $
31   */
32  public interface Value extends Serializable  
33  {
34  
35     // ***********************
36     // * Mono valued methods *
37     // ***********************
38  
39     /**
40      * Return true if the value is null.
41      */
42     boolean isNull();
43  
44     /**
45      * Return the value as a string.
46      */
47     String   asString();
48  
49     /**
50      * Return the value as an int.
51      *
52      * @throws NullConversionException if one of the values is null
53      * @throws FormatConversionException if one of the values cannot be converted
54      */
55     int asInt() throws NullConversionException, FormatConversionException;
56  
57     /**
58      * Return the value as a boolean.
59      *
60      * @throws NullConversionException if one of the values is null
61      * @throws FormatConversionException if one of the values cannot be converted
62      */
63     boolean asBoolean() throws NullConversionException, FormatConversionException;
64  
65     /**
66      * Return the value.
67      *
68      */
69     Object   asObject();
70  
71     // ************************
72     // * Multi valued methods *
73     // ************************
74  
75     /**
76      * Return true if it contains more than one value.
77      */
78     boolean isMultiValued();
79  
80     /**
81      * Return the values as an array of string.
82      */
83     String  [] asStringArray();
84  
85     /**
86      * Return the values as an array of int.
87      *
88      * @throws NullConversionException if one of the values is null
89      * @throws FormatConversionException if one of the values cannot be converted
90      */
91     int[] asIntArray() throws NullConversionException, FormatConversionException;
92  
93     /**
94      * Return the values as an array of boolean.
95      *
96      * @throws NullConversionException if one of the values is null
97      * @throws FormatConversionException if one of the values cannot be converted
98      */
99     boolean[] asBooleanArray() throws NullConversionException, FormatConversionException;
100 
101    /**
102     * Return the values as an array of converted object.
103     */
104    Object  [] asObjectArray();
105 
106    /**
107     * Return the values as an immutable collection of converted object or null.
108     */
109    List   asObjectList();
110 }
111
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