Jackson Data Binding Source Code

Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

  • Jackson Data Binding module allows you to converts JSON to and from POJO (Plain Old Java Object) using property accessor or using annotations.
  • Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.12.4-sources.jar). You can download it at Jackson Maven Website.

    You can also browse Jackson Databind Source Code below:

    ✍: FYIcenter.com

    com/fasterxml/jackson/databind/node/NullNode.java

    package com.fasterxml.jackson.databind.node;
    
    import java.io.IOException;
    
    import com.fasterxml.jackson.core.*;
    import com.fasterxml.jackson.databind.JsonNode;
    import com.fasterxml.jackson.databind.SerializerProvider;
    
    
    /**
     * This singleton value class is used to contain explicit JSON null
     * value.
     */
    public class NullNode
        extends ValueNode
    {
        // // Just need a fly-weight singleton
    
        private static final long serialVersionUID = 1L;
    
        public final static NullNode instance = new NullNode();
    
        /**
         *<p>
         * NOTE: visibility raised to `protected` in 2.9.3 to allow custom subtypes.
         */
        protected NullNode() { }
    
        // To support JDK serialization, recovery of Singleton instance
        protected Object readResolve() {
            return instance;
        }
        
        public static NullNode getInstance() { return instance; }
    
        @Override
        public JsonNodeType getNodeType() {
            return JsonNodeType.NULL;
        }
    
        @Override public JsonToken asToken() { return JsonToken.VALUE_NULL; }
    
        @Override public String asText(String defaultValue) { return defaultValue; }
        @Override public String asText() { return "null"; }
    
        @SuppressWarnings("unchecked")
        @Override
        public JsonNode requireNonNull() {
            return _reportRequiredViolation("requireNonNull() called on `NullNode`");
        }
    
        // as with MissingNode, not considered number node; hence defaults are returned if provided
        
        /*
        public int asInt(int defaultValue);
        public long asLong(long defaultValue);
        public double asDouble(double defaultValue);
        public boolean asBoolean(boolean defaultValue);
        */
        
        @Override
        public final void serialize(JsonGenerator g, SerializerProvider provider)
            throws IOException
        {
            provider.defaultSerializeNull(g);
        }
    
        @Override
        public boolean equals(Object o) {
            // 29-Aug-2019, tatu: [databind#2433] Since custom sub-classes are allowed (bad idea probably),
            //     need to do better comparison
            return (o == this) || (o instanceof NullNode);
        }
    
        @Override
        public int hashCode() {
            return JsonNodeType.NULL.ordinal();
        }
    }
    

    com/fasterxml/jackson/databind/node/NullNode.java

     

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    2022-03-29, 31945👍, 0💬