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Various JSON helper classes and utilities based on Jackson. This also provides as compile dependencies the Jackson annotations, core, databind, datatype-jdk8, module-jaxb-annotations, and datatype-jsr310 modules along with snakeyaml. Therefore you only need to declare this library as a dependency in order to include those other dependencies.

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package edu.byu.hbll.json;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
import com.fasterxml.jackson.databind.node.MissingNode;
import com.fasterxml.jackson.databind.node.NullNode;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * A convenience class for working with {@link JsonNode}s. The {@link JsonNode} is very powerful;
 * however, many common operations are difficult to execute. This fixes many of the problems by
 * wrapping a {@link JsonNode} node and exposing the operations through a simpler API. This also
 * holds the key or field name of a {@link JsonNode} when appropriate and not just the value.
 */
public class JsonField implements Iterable {

  private String key;
  private JsonNode value;

  /**
   * Creates a new {@link JsonField} from the given {@link JsonNode}.
   *
   * @param value the json node value
   */
  public JsonField(JsonNode value) {
    this("0", value);
  }

  /**
   * Creates a new {@link JsonField} with the given field name and from the given {@link JsonNode}.
   *
   * @param key the key or field name
   * @param value the json node value
   */
  public JsonField(String key, JsonNode value) {
    this.key = Objects.requireNonNull(key);
    this.value = Objects.requireNonNull(value);
  }

  /**
   * Same as {@link JsonNode#fieldNames()} with the following exceptions.
   *
   * 
   *   The field names are returned in a list rather than an iterator.
   *   
This works for arrays and value nodes as well. For arrays, the field name is the index of
   *       the element. For value nodes, the field name is always "0".
   * 
   *
   * @return the child field names for objects, the element indexes for arrays, and "0" for value
   *     nodes
   */
  public List fieldNames() {
    List fieldNames = this.stream().map(JsonField::getKey).collect(Collectors.toList());
    return fieldNames;
  }

  /**
   * Same as {@link JsonNode#fields()} with the following exceptions.
   *
   * 
   *   The fields are returned in a list of {@link JsonField}s rather than an iterator of {@link
   *       JsonNode}s.
   *   
The fields contain the key as well as the value.
   *   
This works for arrays and value nodes as well. For arrays, the key is the index of the
   *       element. For value nodes, the key is always "0" and the value is the node itself. {@link
   *       MissingNode}s and {@link NullNode}s are not iterated.
   * 
   *
   * @return the child fields for objects, the elements for arrays, the node itself for value nodes
   */
  public List fields() {
    List nodes = new ArrayList<>();

    if (value.isObject()) {
      // if object return child fields
      Iterator> fields = value.fields();

      while (fields.hasNext()) {
        Map.Entry field = fields.next();
        nodes.add(new JsonField(field.getKey(), field.getValue()));
      }
    } else if (value.isArray()) {
      // if array return elements with key being the index
      int key = 0;

      for (JsonNode value : value) {
        nodes.add(new JsonField("" + (key++), value));
      }
    } else if (value.isMissingNode() || value.isNull()) {
      // do nothing
    } else {
      // if value node return self
      nodes.add(new JsonField("0", value));
    }

    return nodes;
  }

  /**
   * Returns the key or field name.
   *
   * @return the key or field name
   */
  public String getKey() {
    return key;
  }

  /**
   * Returns the {@link JsonNode} value.
   *
   * @return the json node value
   */
  public JsonNode getValue() {
    return value;
  }

  @Override
  public String toString() {
    return JsonNodeFactory.instance.textNode(key) + ":" + value;
  }

  @Override
  public Iterator iterator() {
    return fields().iterator();
  }

  /**
   * Returns a stream based on the {@link #fields} call.
   *
   * @return the field stream
   */
  public Stream stream() {
    return fields().stream();
  }
}