### Question:
JsonUtil { public static ObjectNode createObjectNode() { return mapper.createObjectNode(); }  static String getJsonString(Object obj); static T getJsonObject(String jsonString, Class<T> clazz); static T getJsonObjectArray(String jsonString, TypeReference<T> jsonTypeReference); static String getJsonNodeAsText(String jsonKey, String content); static Iterator<JsonNode> getJsonNodes(String jsonKey, String content); static JsonNode getJsonNode(String jsonKey, String content); static JsonNode getJsonNode(String content); static ObjectNode createObjectNode(); static ArrayNode createArrayNode();  }### Answer:
@Test public void test1(){ ObjectNode root = JsonUtil.createObjectNode(); ObjectNode node1 = JsonUtil.createObjectNode(); ObjectNode node2 = JsonUtil.createObjectNode(); node2.put("zhang", 1); node1.put("aaaa", "1111"); node1.set("bbb", node2); root.set("child",node1); System.out.println(root.toString()); }