Convert json format map string to Map

ObjectMapper objectMapper = new ObjectMapper();
                Map<String, List<CodeInfoDTO>> maps = null;
                try {
                    maps = objectMapper.readValue(entity.getCodeInfo(), Map.class);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                System.out.println(maps.size());
                Set<String> key = maps.keySet();
                Iterator<String> iter = key.iterator();
                while (iter.hasNext()) {
                    String field = iter.next();
                    System.out.println(field + ":" + maps.get(field));
                }