package koukay.Controller.Controllers; import koukay.Portal.webservices.Entity.User; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.ArrayList; import java.util.Date; import java.util.HashMap; import java.util.List; import static java.util.stream.Collectors.toList; public class A { public static void main(String[] args) { List<User> list= new ArrayList(); for (int i = 0; i <5 ; i++) { User user = new User(); user.setCode("code"+i); user.setName("name"+i); user.setBirthday(new Date()); list.add(user); } ObjectMapper objectMapper = new ObjectMapper(); List<HashMap> collect = list.stream() .map(f -> objectMapper.convertValue(f, HashMap.class)) .collect(toList()); System.out.println("--------------"+collect.get(0).keySet()); } }