How to access the value of nested JSON Elements

Question

I found some code for my question but that dose not work in my case

I have a JSON say

{  
   "A":{  
      "B":{  
         "STATUS":"ok",
         "TYPE":"Unknown",
         "NAME":"UnchangedECN"
      }
   }
}

How do I fetch the value of Status Type and Name?

Here is what I've tried

long A ;
String STATUS = "";
String TYPE = "";
String NAME = "";

ObjectMapper mapper = new ObjectMapper();
JsonNode root = mapper.readTree(new File("BOM.json"));

// Get id
A = root.path("A").asLong();
System.out.println("A : " + A);

// Get Name
JsonNode nameNode = root.path("A");
if (nameNode.isMissingNode()) {
    // if "name" node is missing
} else {
    STATUS = nameNode.path("STATUS").asText();
    // missing node, just return empty string
    TYPE = nameNode.path("TYPE").asText();
    NAME = nameNode.path("NAME").asText();

    System.out.println("STATUS : " + STATUS);
    System.out.println("TYPE : " + TYPE);
    System.out.println("NAME : " + NAME);
}

Answer 1

You can use a JSON library to make it easier to deal with. For example, using the org.json maven dependency:

<dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20160212</version>
</dependency>

I used the following code to "unwrap" the desired JSONObject:

@Test
public void foo() {
    String jsonString = "{'A':{'B':{'STATUS':'ok','TYPE':'Unknown','NAME':'UnchangedECN'}}}";
    JSONObject object = new JSONObject(jsonString);
    JSONObject a = object.getJSONObject("A");
    JSONObject b = a.getJSONObject("B");
    System.out.println(b.getString("STATUS"));
    System.out.println(b.getString("TYPE"));
    System.out.println(b.getString("NAME"));
}

Which spit out the following output:

ok
Unknown
UnchangedECN