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Core annotations used for value types, used by Jackson data binding package.

There is a newer version: 2.18.2

package com.fasterxml.jackson.annotation;

/**
 * Optional Boolean value ("nullean"). Needed just because Java annotations
 * can not take 'null' as a value (even as default), so there is no
 * way to distinguish between explicit `true` and `false`, and lack of
 * choice (related: annotations are limited to primitives, so
 * {@link java.lang.Boolean} not allowed as solution).
 *
 * Note: although the use of `true` and `false` would be more convenient, they
 * can not be chosen since they are Java keyword and compiler won't allow
 * the choice. And since enum naming convention suggests all-upper-case,
 * that is what is done here.
 *
 * @since 2.6
 */
public enum OptBoolean
{
    /**
     * Value that indicates that the annotation property is explicitly defined to
     * be enabled, or true.
     */
    TRUE,

    /**
     * Value that indicates that the annotation property is explicitly defined to
     * be disabled, or false.
     */
    FALSE,

    /**
     * Value that indicates that the annotation property does NOT have an explicit
     * definition of enabled/disabled (or true/false); instead, a higher-level
     * configuration value is used; or lacking higher-level global setting,
     * default.
     */
    DEFAULT;

    public Boolean asBoolean() {
        if (this == DEFAULT) return null;
        return (this == TRUE) ? Boolean.TRUE : Boolean.FALSE;
    }

    public boolean asPrimitive() {
        return (this == TRUE);
    }

    public static OptBoolean fromBoolean(Boolean b) {
        if (b == null) {
            return DEFAULT;
        }
        return b.booleanValue() ? TRUE : FALSE;
    }

    public static boolean equals(Boolean b1, Boolean b2) {
        if (b1 == null) {
            return (b2 == null);
        }
        return b1.equals(b2);
    }
}