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

Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/ser/std/NullSerializer.java

package com.fasterxml.jackson.databind.ser.std;

import java.lang.reflect.Type;
import java.io.IOException;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;

/**
 * This is a simple dummy serializer that will just output literal
 * JSON null value whenever serialization is requested.
 * Used as the default "null serializer" (which is used for serializing
 * null object references unless overridden), as well as for some
 * more exotic types (java.lang.Void).
 */
@JacksonStdImpl
@SuppressWarnings("serial")
public class NullSerializer
    extends StdSerializer<Object>
{
    public final static NullSerializer instance = new NullSerializer();
    
    private NullSerializer() { super(Object.class); }
    
    @Override
    public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeNull();
    }

    /**
     * Although this method should rarely get called, for convenience we should override
     * it, and handle it same way as "natural" types: by serializing exactly as is,
     * without type decorations. The most common possible use case is that of delegation
     * by JSON filter; caller cannot know what kind of serializer it gets handed.
     */
    @Override
    public void serializeWithType(Object value, JsonGenerator gen, SerializerProvider serializers,
            TypeSerializer typeSer)
        throws IOException
    {
        gen.writeNull();
    }
    
    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) throws JsonMappingException {
        return createSchemaNode("null");
    }
    
    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint) throws JsonMappingException {
        visitor.expectNullFormat(typeHint);
    }
}

⏎ com/fasterxml/jackson/databind/ser/std/NullSerializer.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
Download 

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⇑⇑ Jackson - Java JSON library