public static String addIdIntoJsonString(Long id, String jsonString) throws AlreadyExistException { if(jsonString ==null) { jsonString = "["; }else{ jsonString = jsonString.replace("]",""); boolean alreadyExist = Arrays.stream(jsonString.replace("[","").split(",")) .anyMatch((empId)-> Long.parseLong(empId.trim())== id); if(alreadyExist){ throw new AlreadyExistException("employeeId '" + id + "' already exist"); } jsonString = jsonString + ","; } jsonString = jsonString + id.toString() + "]"; return jsonString; }

## Run