### Question:
Util { public static String extractUserNickName(String json) { JsonParser jp = new JsonParser(); JsonElement je = jp.parse(json); JsonElement resultUserInfo = JsonUtil.getValueOfVar(je, "resultUserInfo"); JsonElement nickname = JsonUtil.getValueOfVar(resultUserInfo, "userName"); return nickname.getAsString(); }  static String extractUserNickName(String json);  }### Answer:
@Test public void extractUserNicknameTest() { String input = "{\n" + " \"resultUserInfo\": {\n" + " \"userId\": \"test123\",\n" + " \"userName\": \"test123_name\"\n" + " },\n" + " \"resultType\": \"SUCCESS\"\n" + " }"; String userNickname = Util.extractUserNickName(input); System.out.print(userNickname); }