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/node/ArrayNode.java

package com.fasterxml.jackson.databind.node;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.type.WritableTypeId;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.util.RawValue;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

/**
 * Node class that represents Arrays mapped from JSON content.
 *<p>
 * Note: class was <code>final</code> temporarily for Jackson 2.2.
 */
public class ArrayNode
    extends ContainerNode<ArrayNode>
    implements java.io.Serializable // since 2.10
{
    private static final long serialVersionUID = 1L;

    private final List<JsonNode> _children;

    public ArrayNode(JsonNodeFactory nf) {
        super(nf);
        _children = new ArrayList<JsonNode>();
    }

    /**
     * @since 2.8
     */
    public ArrayNode(JsonNodeFactory nf, int capacity) {
        super(nf);
        _children = new ArrayList<JsonNode>(capacity);
    }

    /**
     * @since 2.7
     */
    public ArrayNode(JsonNodeFactory nf, List<JsonNode> children) {
        super(nf);
        _children = children;
    }

    @Override
    protected JsonNode _at(JsonPointer ptr) {
        return get(ptr.getMatchingIndex());
    }

    // note: co-variant to allow caller-side type safety
    @SuppressWarnings("unchecked")
    @Override
    public ArrayNode deepCopy()
    {
        ArrayNode ret = new ArrayNode(_nodeFactory);

        for (JsonNode element: _children)
            ret._children.add(element.deepCopy());

        return ret;
    }

    /*
    /**********************************************************
    /* Overrides for JsonSerializable.Base
    /**********************************************************
     */

    @Override
    public boolean isEmpty(SerializerProvider serializers) {
        return _children.isEmpty();
    }

    /*
    /**********************************************************
    /* Implementation of core JsonNode API
    /**********************************************************
     */

    @Override
    public JsonNodeType getNodeType() {
        return JsonNodeType.ARRAY;
    }

    @Override
    public boolean isArray() {
        return true;
    }

    @Override public JsonToken asToken() { return JsonToken.START_ARRAY; }

    @Override
    public int size() {
        return _children.size();
    }

    @Override // since 2.10
    public boolean isEmpty() { return _children.isEmpty(); }

    @Override
    public Iterator<JsonNode> elements() {
        return _children.iterator();
    }

    @Override
    public JsonNode get(int index) {
        if ((index >= 0) && (index < _children.size())) {
            return _children.get(index);
        }
        return null;
    }

    @Override
    public JsonNode get(String fieldName) { return null; }

    @Override
    public JsonNode path(String fieldName) { return MissingNode.getInstance(); }

    @Override
    public JsonNode path(int index) {
        if (index >= 0 && index < _children.size()) {
            return _children.get(index);
        }
        return MissingNode.getInstance();
    }

    @Override
    public JsonNode required(int index) {
        if ((index >= 0) && (index < _children.size())) {
            return _children.get(index);
        }
        return _reportRequiredViolation("No value at index #%d [0, %d) of `ArrayNode`",
                index, _children.size());
    }

    @Override
    public boolean equals(Comparator<JsonNode> comparator, JsonNode o)
    {
        if (!(o instanceof ArrayNode)) {
            return false;
        }
        ArrayNode other = (ArrayNode) o;
        final int len = _children.size();
        if (other.size() != len) {
            return false;
        }
        List<JsonNode> l1 = _children;
        List<JsonNode> l2 = other._children;
        for (int i = 0; i < len; ++i) {
            if (!l1.get(i).equals(comparator, l2.get(i))) {
                return false;
            }
        }
        return true;
    }

    /*
    /**********************************************************
    /* Public API, serialization
    /**********************************************************
     */

    @Override
    public void serialize(JsonGenerator f, SerializerProvider provider) throws IOException
    {
        final List<JsonNode> c = _children;
        final int size = c.size();
        f.writeStartArray(this, size);
        for (int i = 0; i < size; ++i) { // we'll typically have array list
            // For now, assuming it's either BaseJsonNode, JsonSerializable
            JsonNode n = c.get(i);
            ((BaseJsonNode) n).serialize(f, provider);
        }
        f.writeEndArray();
    }

    @Override
    public void serializeWithType(JsonGenerator g, SerializerProvider provider, TypeSerializer typeSer)
        throws IOException
    {
        WritableTypeId typeIdDef = typeSer.writeTypePrefix(g,
                typeSer.typeId(this, JsonToken.START_ARRAY));
        for (JsonNode n : _children) {
            ((BaseJsonNode)n).serialize(g, provider);
        }
        typeSer.writeTypeSuffix(g, typeIdDef);
    }

    /*
    /**********************************************************
    /* Public API, finding value nodes
    /**********************************************************
     */

    @Override
    public JsonNode findValue(String fieldName)
    {
        for (JsonNode node : _children) {
            JsonNode value = node.findValue(fieldName);
            if (value != null) {
                return value;
            }
        }
        return null;
    }

    @Override
    public List<JsonNode> findValues(String fieldName, List<JsonNode> foundSoFar)
    {
        for (JsonNode node : _children) {
            foundSoFar = node.findValues(fieldName, foundSoFar);
        }
        return foundSoFar;
    }

    @Override
    public List<String> findValuesAsText(String fieldName, List<String> foundSoFar)
    {
        for (JsonNode node : _children) {
            foundSoFar = node.findValuesAsText(fieldName, foundSoFar);
        }
        return foundSoFar;
    }

    @Override
    public ObjectNode findParent(String fieldName)
    {
        for (JsonNode node : _children) {
            JsonNode parent = node.findParent(fieldName);
            if (parent != null) {
                return (ObjectNode) parent;
            }
        }
        return null;
    }

    @Override
    public List<JsonNode> findParents(String fieldName, List<JsonNode> foundSoFar)
    {
        for (JsonNode node : _children) {
            foundSoFar = node.findParents(fieldName, foundSoFar);
        }
        return foundSoFar;
    }

    /*
    /**********************************************************
    /* Extended ObjectNode API, accessors
    /**********************************************************
     */

    /**
     * Method that will set specified field, replacing old value,
     * if any.
     *
     * @param value to set field to; if null, will be converted
     *   to a {@link NullNode} first  (to remove field entry, call
     *   {@link #remove} instead)
     *
     * @return Old value of the field, if any; null if there was no
     *   old value.
     */
    public JsonNode set(int index, JsonNode value)
    {
        if (value == null) { // let's not store 'raw' nulls but nodes
            value = nullNode();
        }
        if (index < 0 || index >= _children.size()) {
            throw new IndexOutOfBoundsException("Illegal index "+ index +", array size "+size());
        }
        return _children.set(index, value);
    }

    /**
     * Method for adding specified node at the end of this array.
     *
     * @return This node, to allow chaining
     */
    public ArrayNode add(JsonNode value)
    {
        if (value == null) { // let's not store 'raw' nulls but nodes
            value = nullNode();
        }
        _add(value);
        return this;
    }

    /**
     * Method for adding all child nodes of given Array, appending to
     * child nodes this array contains
     *
     * @param other Array to add contents from
     *
     * @return This node (to allow chaining)
     */
    public ArrayNode addAll(ArrayNode other)
    {
        _children.addAll(other._children);
        return this;
    }

    /**
     * Method for adding given nodes as child nodes of this array node.
     *
     * @param nodes Nodes to add
     *
     * @return This node (to allow chaining)
     */
    public ArrayNode addAll(Collection<? extends JsonNode> nodes)
    {
        for (JsonNode node : nodes) {
            add(node);
        }
        return this;
    }

    /**
     * Method for inserting specified child node as an element
     * of this Array. If index is 0 or less, it will be inserted as
     * the first element; if {@code >= size()}, appended at the end, and otherwise
     * inserted before existing element in specified index.
     * No exceptions are thrown for any index.
     *
     * @return This node (to allow chaining)
     */
    public ArrayNode insert(int index, JsonNode value)
    {
        if (value == null) {
            value = nullNode();
        }
        _insert(index, value);
        return this;
    }

    /**
     * Method for removing an entry from this ArrayNode.
     * Will return value of the entry at specified index, if entry existed;
     * null if not.
     *
     * @return Node removed, if any; null if none
     */
    public JsonNode remove(int index)
    {
        if (index >= 0 && index < _children.size()) {
            return _children.remove(index);
        }
        return null;
    }

    /**
     * Method for removing all elements of this array, leaving the
     * array empty.
     *
     * @return This node (to allow chaining)
     */
    @Override
    public ArrayNode removeAll()
    {
        _children.clear();
        return this;
    }

    /*
    /**********************************************************
    /* Extended ObjectNode API, mutators, generic; addXxx()/insertXxx()
    /**********************************************************
     */

    /**
     * Method that will construct an ArrayNode and add it at the end
     * of this array node.
     *
     * @return Newly constructed ArrayNode
     */
    public ArrayNode addArray()
    {
        ArrayNode n  = arrayNode();
        _add(n);
        return n;
    }

    /**
     * Method that will construct an ObjectNode and add it at the end
     * of this array node.
     *
     * @return Newly constructed ObjectNode
     */
    public ObjectNode addObject()
    {
        ObjectNode n  = objectNode();
        _add(n);
        return n;
    }

    /**
     * Method that will construct a POJONode and add it at the end
     * of this array node.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode addPOJO(Object value)
    {
        if (value == null) {
            addNull();
        } else {
            _add(pojoNode(value));
        }
        return this;
    }

    /**
     * @return This array node, to allow chaining
     *
     * @since 2.6
     */
    public ArrayNode addRawValue(RawValue raw) {
        if (raw == null) {
            addNull();
        } else {
            _add(rawValueNode(raw));
        }
        return this;
    }

    /**
     * Method that will add a null value at the end of this array node.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode addNull()
    {
        _add(nullNode());
        return this;
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(int v) {
        _add(numberNode(v));
        return this;
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(Integer value) {
        if (value == null) {
            return addNull();
        }
        return _add(numberNode(value.intValue()));
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(long v) { return _add(numberNode(v)); }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(Long value) {
        if (value == null) {
            return addNull();
        }
        return _add(numberNode(value.longValue()));
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(float v) {
        return _add(numberNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(Float value) {
        if (value == null) {
            return addNull();
        }
        return _add(numberNode(value.floatValue()));
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(double v) {
        return _add(numberNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(Double value) {
        if (value == null) {
            return addNull();
        }
        return _add(numberNode(value.doubleValue()));
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(BigDecimal v) {
        if (v == null) {
            return addNull();
        }
        return _add(numberNode(v));
    }

    /**
     * Method for adding specified number at the end of this array.
     *
     * @return This array node, to allow chaining
     *
     * @since 2.9
     */
    public ArrayNode add(BigInteger v) {
        if (v == null) {
            return addNull();
        }
        return _add(numberNode(v));
    }
    
    /**
     * Method for adding specified String value at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(String v) {
        if (v == null) {
            return addNull();
        }
        return _add(textNode(v));
    }

    /**
     * Method for adding specified boolean value at the end of this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(boolean v) {
        return _add(booleanNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(Boolean value) {
        if (value == null) {
            return addNull();
        }
        return _add(booleanNode(value.booleanValue()));
    }

    /**
     * Method for adding specified binary value at the end of this array
     * (note: when serializing as JSON, will be output Base64 encoded)
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode add(byte[] v) {
        if (v == null) {
            return addNull();
        }
        return _add(binaryNode(v));
    }

    /**
     * Method for creating an array node, inserting it at the
     * specified point in the array,
     * and returning the <b>newly created array</b>
     * (note: NOT 'this' array)
     */
    public ArrayNode insertArray(int index)
    {
        ArrayNode n  = arrayNode();
        _insert(index, n);
        return n;
    }

    /**
     * Method for creating an {@link ObjectNode}, appending it at the end
     * of this array, and returning the <b>newly created node</b>
     * (note: NOT 'this' array)
     *
     * @return Newly constructed ObjectNode
     */
    public ObjectNode insertObject(int index)
    {
        ObjectNode n  = objectNode();
        _insert(index, n);
        return n;
    }

    /**
     * Method that will construct a POJONode and
     * insert it at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insertPOJO(int index, Object value)
    {
        if (value == null) {
            return insertNull(index);
        }
        return _insert(index, pojoNode(value));
    }

    /**
     * Method that will insert a null value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insertNull(int index)
    {
        _insert(index, nullNode());
        return this;
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, int v) {
        _insert(index, numberNode(v));
        return this;
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, Integer value) {
        if (value == null) {
            insertNull(index);
        } else {
            _insert(index, numberNode(value.intValue()));
        }
        return this;
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, long v) {
        return _insert(index, numberNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, Long value) {
        if (value == null) {
            return insertNull(index);
        }
        return _insert(index, numberNode(value.longValue()));
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, float v) {
        return _insert(index, numberNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, Float value) {
        if (value == null) {
            return insertNull(index);
        }
        return _insert(index, numberNode(value.floatValue()));
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, double v) {
        return _insert(index, numberNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, Double value) {
        if (value == null) {
            return insertNull(index);
        }
        return _insert(index, numberNode(value.doubleValue()));
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, BigDecimal v) {
        if (v == null) {
            return insertNull(index);
        }
        return _insert(index, numberNode(v));
    }

    /**
     * Method that will insert specified numeric value
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     *
     * @since 2.9
     */
    public ArrayNode insert(int index, BigInteger v) {
        if (v == null) {
            return insertNull(index);
        }
        return _insert(index, numberNode(v));
    }
    
    /**
     * Method that will insert specified String
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, String v) {
        if (v == null) {
            return insertNull(index);
        }
        return _insert(index, textNode(v));
    }

    /**
     * Method that will insert specified String
     * at specified position in this array.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, boolean v) {
        return _insert(index, booleanNode(v));
    }

    /**
     * Alternative method that we need to avoid bumping into NPE issues
     * with auto-unboxing.
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, Boolean value) {
        if (value == null) {
            return insertNull(index);
        }
        return _insert(index, booleanNode(value.booleanValue()));
    }

    /**
     * Method that will insert specified binary value
     * at specified position in this array
     * (note: when written as JSON, will be Base64 encoded)
     *
     * @return This array node, to allow chaining
     */
    public ArrayNode insert(int index, byte[] v) {
        if (v == null) {
            return insertNull(index);
        }
        return _insert(index, binaryNode(v));
    }

    /*
    /**********************************************************
    /* Standard methods
    /**********************************************************
     */

    @Override
    public boolean equals(Object o)
    {
        if (o == this) return true;
        if (o == null) return false;
        if (o instanceof ArrayNode) {
            return _children.equals(((ArrayNode) o)._children);
        }
        return false;
    }

    /**
     * @since 2.3
     */
    protected boolean _childrenEqual(ArrayNode other) {
        return _children.equals(other._children);
    }

    @Override
    public int hashCode() {
        return _children.hashCode();
    }

    /*
    /**********************************************************
    /* Internal methods (overridable)
    /**********************************************************
     */

    protected ArrayNode _add(JsonNode node) {
        _children.add(node);
        return this;
    }

    protected ArrayNode _insert(int index, JsonNode node)
    {
        if (index < 0) {
            _children.add(0, node);
        } else if (index >= _children.size()) {
            _children.add(node);
        } else {
            _children.add(index, node);
        }
        return this;
    }
}

⏎ com/fasterxml/jackson/databind/node/ArrayNode.java

 

⇒ Jackson Dataformat Extensions

⇐ Jackson Data Binding Source Code

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library