How to sort GSON Array based on a key?

Question

Consider the following is my Array

[
  {\"id\":10,\"name\":\"name10\",\"valid\":true},
  {\"id\":12,\"name\":\"name12\",\"valid\":false},
  {\"id\":11,\"name         


        

Answer 1

Try this library method as a simple JSON-level alternative to model classes creation:

/**
 * Sort JSON-array by a given key name (numbers or text expected).
 *
 * @param jsonArray     JSON-array to sort.
 * @param keyNameToSort Key name to sort by. Expected are integer type 
 *                      (sorted ascending) or string type (sorted 
 *                      alphabetically).
 */
public static JsonArray
sortJsonArrayByKey(
  JsonArray jsonArray,
  String keyNameToSort) {

  JsonArray sortedJsonArray = new JsonArray();
  JsonObject jsonObject = null;
  int jsonElementIndex;
  TreeMap<Integer, JsonObject> integerSortedObjects = new TreeMap<>();
  TreeMap<String, JsonObject> stringSortedObjects = new TreeMap<>();

  for (
    jsonElementIndex = 0;
    jsonElementIndex < jsonArray.size();
    jsonElementIndex++) {

    try {

      // A JSON-Object from JSON-array:

      jsonObject =
        jsonArray
          .get(
            jsonElementIndex)
          .getAsJsonObject();

    } catch (Exception notAnObject) {
    }

    for (Entry<String, JsonElement> entry : jsonObject.entrySet()) {

      // Look for the given key in the JSON-object:

      if (
        entry.getKey()
        .equals(keyNameToSort)) {

        try {

          // If key is of integer type:

          integerSortedObjects.put(
            entry
              .getValue()
              .getAsInt(),
            jsonObject);

        } catch (Exception notAnInt) {

          try {

            // If key is of string type:

            stringSortedObjects.put(
              entry
                .getValue()
                .getAsString(),
              jsonObject);

          } catch (Exception neitherIntNorString) {
          }
        }
      }
    }
  }

  // Add sorted by number values first:

  for (Integer key : integerSortedObjects.keySet()) {

    sortedJsonArray.add(
      integerSortedObjects.get(
        key));
  }

  // Add sorted by string values second:

  for (String key : stringSortedObjects.keySet()) {

    sortedJsonArray.add(
      stringSortedObjects.get(
        key));
  }

  return sortedJsonArray;
}

Answer 2

First of all, the proper way to parse your JSON is to create a class to encapsulate your data, such as:

public class MyClass {
    private Integer id;
    private String name;
    private Boolean valid;
    //getters & setters
}

And then:

Type listType = new TypeToken<List<MyClass>>() {}.getType();
List<MyClass> myList = new Gson().fromJson(strArrayText, listType);

---

Now you have a List and you want to sort it by the value of the attribute id, so you can use Collections as explained here:

public class MyComparator implements Comparator<MyClass> {
    @Override
    public int compare(MyClass o1, MyClass o2) {
        return o1.getId().compareTo(o2.getId());
    }
}

And finally:

Collections.sort(myList, new MyComparator());

Answer 3

you can use Gson library https://sites.google.com/site/gson/gson-user-guide to get the Array(the class should implement comparable) and sort with arrays.sort();

Thanks