Gson gson = new Gson();
String jsonString = gson.toJson(obj);
MyClass obj = gson.fromJson(jsonString, MyClass.class);
ObjectMapper objectMapper = new ObjectMapper();
String jsonString = objectMapper.writeValueAsString(obj);
MyClass obj = objectMapper.readValue(jsonString, MyClass.class);
JSONObject jsonObject = new JSONObject();
jsonObject.put("key", "value");
String jsonString = jsonObject.toJSONString();
JSONObject newJsonObject = (JSONObject) JSONValue.parse(jsonString);
Jsonb jsonb = JsonbBuilder.create();
String jsonString = jsonb.toJson(obj);
MyClass obj = jsonb.fromJson(jsonString, MyClass.class);