Question

json object from REST service

{
   "destination_addresses" : [ "Chicago, IL, USA" ],
   "origin_addresses" : [ "Syracuse, NY, USA" ],
   "rows" : [
      {
         "elements" : [
            {
               "distance" : {
                  "text" : "1,090 km",
                  "value" : 1090383
               },
               "duration" : {
                  "text" : "10 hours 21 mins",
                  "value" : 37242
               },
               "status" : "OK"
            }
         ]
      }
   ],
   "status" : "OK"
}

Using code from JacksonInFiveMinutes

ObjectMapper mapper = new ObjectMapper();
Map userData = mapper.readValue(webResource.queryParams(queryParams).get(String.class);, Map.class);

Where:

webResource.queryParams(queryParams).get(String.class);

returns the json from REST service

From Json I would like the 2 address properties as well as the distance property as well as the 2 status.

My hack attempt:

ObjectMapper mapper = new ObjectMapper();
JsonNode jnode = mapper.readValue(s, JsonNode.class);
jnode.findValue("distance").findValue("value") // 

this gets me the value I am looking for.

Not sure if this is good way to go about

Answer 1

It looks OK to me, except that it would be safer to not chain those two findValue() calls together, as you could get a NPE if the JSON string doesn’t contain the first one. From the JsonNode javadoc:

public abstract JsonNode findValue(String fieldName)

Method for finding a JSON Object field with specified name in this
node or its child nodes, and returning value it has. If no matching
field is found in this node or its descendants, returns null.

So I’d check the first findValue() result and if its not null, then perform the second findValue() (with logging to notify you if this happens).