1 package com.fasterxml.jackson.annotation;
2 
3 /**
4  * Optional Boolean value ("nullean"). Needed just because Java annotations
5  * can not take 'null' as a value (even as default), so there is no
6  * way to distinguish between explicit `true` and `false`, and lack of
7  * choice (related: annotations are limited to primitives, so
8  * {@link java.lang.Boolean} not allowed as solution).
9  *<p>
10  * Note: although use of `true` and `false` would be more convenient, they
11  * can not be chosen since they are Java keyword and compiler won't allow
12  * the choice. And since enum naming convention suggests all-upper-case,
13  * that is what is done here.
14  *
15  * @since 2.6
16  */
17 public enum OptBoolean
18 {
19     /**
20      * Value that indicates that the annotation property is explicitly defined to
21      * be enabled, or true.
22      */
23     TRUE,
24 
25     /**
26      * Value that indicates that the annotation property is explicitly defined to
27      * be disabled, or false.
28      */
29     FALSE,
30 
31     /**
32      * Value that indicates that the annotation property does NOT have an explicit
33      * definition of enabled/disabled (or true/false); instead, a higher-level
34      * configuration value is used; or lacking higher-level global setting,
35      * default.
36      */
37     DEFAULT;
38 
asBoolean()39     public Boolean asBoolean() {
40         if (this == DEFAULT) return null;
41         return (this == TRUE) ? Boolean.TRUE : Boolean.FALSE;
42     }
43 
asPrimitive()44     public boolean asPrimitive() {
45         return (this == TRUE);
46     }
47 
fromBoolean(Boolean b)48     public static OptBoolean fromBoolean(Boolean b) {
49         if (b == null) {
50             return DEFAULT;
51         }
52         return b.booleanValue() ? TRUE : FALSE;
53     }
54 
equals(Boolean b1, Boolean b2)55     public static boolean equals(Boolean b1, Boolean b2) {
56         if (b1 == null) {
57             return (b2 == null);
58         }
59         return b1.equals(b2);
60     }
61 }
62