How to get a value from a JSON string using jackson library?

Question

I am trying to get a value from a JSON string but I am getting a null value instead.

App2.java :

package JsonExample1;

import org.codehaus.jackson.J         


        

Answer 1

Convert to the Map

Map map = objectMapper.readValue(jsonString, Map.class);

Method for navigation in the map

private static <T> T get(Map map, Class<T> clazz, String... path) {
    Map node = map;
    for (int i = 0; i < path.length - 1; i++) {
      node = (Map) node.get(path[i]);
    }
    return (T) node.get(path[path.length - 1]);
  }

Usage:

String value = get(map, String.class, "path", "to", "the", "node")

Answer 2

Your root node doesn't have a customerSessionId, it has a HotelListResponse. Get that first.

//other methods
public void basicTreeModelRead()
{
    JsonNode innerNode = rootNode.get("HotelListResponse"); // Get the only element in the root node
    // get an element in that node
    JsonNode aField = innerNode.get("customerSessionId");

    //the customerSessionId has a String value
    String myString = aField.asText();

    System.out.println("customerSessionId is:" + myString);
}

This prints

customerSessionId is:0ABAAA7A-90C9-7491-3FF2-7E2C37496CA2

Answer 3

Another way to get the inner element, with .at() method:

rootNode.at("/HotelListResponse/customerSessionId")