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

ReactNativeJson.java

public static WritableMap convertJsonToMap(@NonNull JSONObject jsonObject) throws JSONException {
    WritableMap map = Arguments.createMap();

    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 Long) {
            map.putDouble(key, ((Long) value).doubleValue());
        } else if (value instanceof Double) {
            map.putDouble(key, (Double) value);
        } else if (value instanceof String) {
            map.putString(key, (String) value);
        } else if (value == JSONObject.NULL) {
            map.putNull(key);
        } else {
            // value != null since jsonObject.put("key", null) removes value for "key"
            map.putString(key, value.toString());
        }
    }
    return map;
}

public static WritableArray convertJsonToArray(@NonNull JSONArray jsonArray) throws JSONException {
    WritableArray array = Arguments.createArray();

    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 Long) {
            array.pushDouble(((Long) value).doubleValue());
        } else if (value instanceof Double) {
            array.pushDouble((Double) value);
        } else if (value instanceof String) {
            array.pushString((String) value);
        } else if (value == JSONObject.NULL) {
            array.pushNull();
        } else {
            // value != null since jsonArray.get() throws in this case
            array.pushString(value.toString());
        }
    }
    return array;
}

public static JSONObject convertMapToJson(@NonNull 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:
                //noinspection ConstantConditions
                object.put(key, convertMapToJson(readableMap.getMap(key)));
                break;
            case Array:
                //noinspection ConstantConditions
                object.put(key, convertArrayToJson(readableMap.getArray(key)));
                break;
        }
    }
    return object;
}

public static JSONArray convertArrayToJson(@NonNull ReadableArray readableArray) throws JSONException {
    JSONArray array = new JSONArray();

    for (int i = 0; i < readableArray.size(); i++) {
        switch (readableArray.getType(i)) {
            case Null:
                array.put(JSONObject.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;
}

• Added Null type / JSONObject.NULL handling
• Added Long type handling