React-Native Module, ReadableMap/Array to Java JSON objects

ReactNativeJson.java

private static WritableMap convertJsonToMap(JSONObject jsonObject) throws JSONException {
    WritableMap map = new WritableNativeMap();

    Iterator<String> iterator = jsonObject.keys();
    while (iterator.hasNext()) {
        String key = iterator.next();
        Object value = jsonObject.get(key);
        if (value instanceof JSONObject) {
            map.putMap(key, convertJsonToMap((JSONObject) value));
        } else if (value instanceof  JSONArray) {
            map.putArray(key, convertJsonToArray((JSONArray) value));
        } else if (value instanceof  Boolean) {
            map.putBoolean(key, (Boolean) value);
        } else if (value instanceof  Integer) {
            map.putInt(key, (Integer) value);
        } else if (value instanceof  Double) {
            map.putDouble(key, (Double) value);
        } else if (value instanceof String)  {
            map.putString(key, (String) value);
        } else {
            map.putString(key, value.toString());
        }
    }
    return map;
}

private static WritableArray convertJsonToArray(JSONArray jsonArray) throws JSONException {
    WritableArray array = new WritableNativeArray();

    for (int i = 0; i < jsonArray.length(); i++) {
        Object value = jsonArray.get(i);
        if (value instanceof JSONObject) {
            array.pushMap(convertJsonToMap((JSONObject) value));
        } else if (value instanceof  JSONArray) {
            array.pushArray(convertJsonToArray((JSONArray) value));
        } else if (value instanceof  Boolean) {
            array.pushBoolean((Boolean) value);
        } else if (value instanceof  Integer) {
            array.pushInt((Integer) value);
        } else if (value instanceof  Double) {
            array.pushDouble((Double) value);
        } else if (value instanceof String)  {
            array.pushString((String) value);
        } else {
            array.pushString(value.toString());
        }
    }
    return array;
}

private static JSONObject convertMapToJson(ReadableMap readableMap) throws JSONException {
    JSONObject object = new JSONObject();
    ReadableMapKeySetIterator iterator = readableMap.keySetIterator();
    while (iterator.hasNextKey()) {
        String key = iterator.nextKey();
        switch (readableMap.getType(key)) {
            case Null:
                object.put(key, JSONObject.NULL);
                break;
            case Boolean:
                object.put(key, readableMap.getBoolean(key));
                break;
            case Number:
                object.put(key, readableMap.getDouble(key));
                break;
            case String:
                object.put(key, readableMap.getString(key));
                break;
            case Map:
                object.put(key, convertMapToJson(readableMap.getMap(key)));
                break;
            case Array:
                object.put(key, convertArrayToJson(readableMap.getArray(key)));
                break;
        }
    }
    return object;
}

private static JSONArray convertArrayToJson(ReadableArray readableArray) throws JSONException {
    JSONArray array = new JSONArray();
    for (int i = 0; i < readableArray.size(); i++) {
        switch (readableArray.getType(i)) {
            case Null:
                break;
            case Boolean:
                array.put(readableArray.getBoolean(i));
                break;
            case Number:
                array.put(readableArray.getDouble(i));
                break;
            case String:
                array.put(readableArray.getString(i));
                break;
            case Map:
                array.put(convertMapToJson(readableArray.getMap(i)));
                break;
            case Array:
                array.put(convertArrayToJson(readableArray.getArray(i)));
                break;
        }
    }
    return array;
}

Why do you ignore values with type Null in convertArrayToJson() method? null is correct JSON value and can be stored in JSONArray via JSONObject.NULL.