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

Jackson Annotations Source Code files are provided in the source packge (jackson-annotations-2.12.4-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Annotations Source Code below:

⏎ com/fasterxml/jackson/databind/ser/impl/IndexedListSerializer.java

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

import java.io.IOException;
import java.util.*;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.ser.ContainerSerializer;
import com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase;

/**
 * This is an optimized serializer for Lists that can be efficiently
 * traversed by index (as opposed to others, such as {@link LinkedList}
 * that cannot}.
 */
@JacksonStdImpl
public final class IndexedListSerializer
    extends AsArraySerializerBase<List<?>>
{
    private static final long serialVersionUID = 1L;

    public IndexedListSerializer(JavaType elemType, boolean staticTyping, TypeSerializer vts,
            JsonSerializer<Object> valueSerializer)
    {
        super(List.class, elemType, staticTyping, vts, valueSerializer);
    }

    public IndexedListSerializer(IndexedListSerializer src,
            BeanProperty property, TypeSerializer vts, JsonSerializer<?> valueSerializer,
            Boolean unwrapSingle) {
        super(src, property, vts, valueSerializer, unwrapSingle);
    }

    @Override
    public IndexedListSerializer withResolved(BeanProperty property,
            TypeSerializer vts, JsonSerializer<?> elementSerializer,
            Boolean unwrapSingle) {
        return new IndexedListSerializer(this, property, vts, elementSerializer, unwrapSingle);
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */
    
    @Override
    public boolean isEmpty(SerializerProvider prov, List<?> value) {
        return value.isEmpty();
    }

    @Override
    public boolean hasSingleElement(List<?> value) {
        return (value.size() == 1);
    }

    @Override
    public ContainerSerializer<?> _withValueTypeSerializer(TypeSerializer vts) {
        return new IndexedListSerializer(this, 
                _property, vts, _elementSerializer, _unwrapSingle);
    }

    @Override
    public final void serialize(List<?> value, JsonGenerator gen, SerializerProvider provider)
        throws IOException
    {
        final int len = value.size();
        if (len == 1) {
            if (((_unwrapSingle == null) &&
                    provider.isEnabled(SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED))
                    || (_unwrapSingle == Boolean.TRUE)) {
                serializeContents(value, gen, provider);
                return;
            }
        }
        gen.writeStartArray(value, len);
        serializeContents(value, gen, provider);
        gen.writeEndArray();
    }
    
    @Override
    public void serializeContents(List<?> value, JsonGenerator g, SerializerProvider provider)
        throws IOException
    {
        if (_elementSerializer != null) {
            serializeContentsUsing(value, g, provider, _elementSerializer);
            return;
        }
        if (_valueTypeSerializer != null) {
            serializeTypedContents(value, g, provider);
            return;
        }
        final int len = value.size();
        if (len == 0) {
            return;
        }
        int i = 0;
        try {
            PropertySerializerMap serializers = _dynamicSerializers;
            for (; i < len; ++i) {
                Object elem = value.get(i);
                if (elem == null) {
                    provider.defaultSerializeNull(g);
                } else {
                    Class<?> cc = elem.getClass();
                    JsonSerializer<Object> serializer = serializers.serializerFor(cc);
                    if (serializer == null) {
                        // To fix [JACKSON-508]
                        if (_elementType.hasGenericTypes()) {
                            serializer = _findAndAddDynamic(serializers,
                                    provider.constructSpecializedType(_elementType, cc), provider);
                        } else {
                            serializer = _findAndAddDynamic(serializers, cc, provider);
                        }
                        serializers = _dynamicSerializers;
                    }
                    serializer.serialize(elem, g, provider);
                }
            }
        } catch (Exception e) {
            wrapAndThrow(provider, e, value, i);
        }
    }
    
    public void serializeContentsUsing(List<?> value, JsonGenerator jgen, SerializerProvider provider,
            JsonSerializer<Object> ser)
        throws IOException
    {
        final int len = value.size();
        if (len == 0) {
            return;
        }
        final TypeSerializer typeSer = _valueTypeSerializer;
        for (int i = 0; i < len; ++i) {
            Object elem = value.get(i);
            try {
                if (elem == null) {
                    provider.defaultSerializeNull(jgen);
                } else if (typeSer == null) {
                    ser.serialize(elem, jgen, provider);
                } else {
                    ser.serializeWithType(elem, jgen, provider, typeSer);
                }
            } catch (Exception e) {
                // [JACKSON-55] Need to add reference information
                wrapAndThrow(provider, e, value, i);
            }
        }
    }

    public void serializeTypedContents(List<?> value, JsonGenerator jgen, SerializerProvider provider)
        throws IOException
    {
        final int len = value.size();
        if (len == 0) {
            return;
        }
        int i = 0;
        try {
            final TypeSerializer typeSer = _valueTypeSerializer;
            PropertySerializerMap serializers = _dynamicSerializers;
            for (; i < len; ++i) {
                Object elem = value.get(i);
                if (elem == null) {
                    provider.defaultSerializeNull(jgen);
                } else {
                    Class<?> cc = elem.getClass();
                    JsonSerializer<Object> serializer = serializers.serializerFor(cc);
                    if (serializer == null) {
                        // To fix [JACKSON-508]
                        if (_elementType.hasGenericTypes()) {
                            serializer = _findAndAddDynamic(serializers,
                                    provider.constructSpecializedType(_elementType, cc), provider);
                        } else {
                            serializer = _findAndAddDynamic(serializers, cc, provider);
                        }
                        serializers = _dynamicSerializers;
                    }
                    serializer.serializeWithType(elem, jgen, provider, typeSer);
                }
            }
        } catch (Exception e) {
            wrapAndThrow(provider, e, value, i);
        }
    }
}

⏎ com/fasterxml/jackson/databind/ser/impl/IndexedListSerializer.java

 

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