如何使用Java代码从具有嵌套数据的Json数组中获取值

Question

I have to fetch the value from array "machines" having nested data and need to fetch for "value1": "Need to fetch this value". Tried a lot of code but still not able to fetch the same.

{
   "name":"anyname",
   "machines":[
      {
         "id":"771760",
         "type":"general",
         "properties":{
            "value1":"1",
            "value2":"2"
         }
      },
      {
         "id":"341256",
         "type":"general",
         "properties":{
            "value1":"Need to fetch this value"
         }
      },
      {
         "id":"341256",
         "type":"general",
         "properties":{
            "value1":"1",
            "value2":"2"
         }
      }
   ]
}

Tried using JsonObject and JsonArray, Still not worked

public String getValueForAnyKeyHavingNestedObjects(String jsonData,String outerObjectKey, String keyWhoseValueToFetch) throws JSONException {

JSONObject obj = new JSONObject(jsonData);

String value = String.valueOf(obj.getJSONObject(outerObjectKey).get(keyWhoseValueToFetch));
return value;
}

Answer 1

So you have your jsonData which you need to put in a JSONObject .

You need to extract the machines, which is an array using getJSONArray("machines") .

After that, you want to iterate over each machine and convert the machine into another JSONObject .

In order to take the value1, you just do a normal get("value1") .

Full example here:

public static void main(String[] args) {
        String jsonData = "{\n"
                + "   \"name\":\"anyname\",\n"
                + "   \"machines\":[\n"
                + "      {\n"
                + "         \"id\":\"771760\",\n"
                + "         \"type\":\"general\",\n"
                + "         \"properties\":{\n"
                + "            \"value1\":\"1\",\n"
                + "            \"value2\":\"2\"\n"
                + "         }\n"
                + "      },\n"
                + "      {\n"
                + "         \"id\":\"341256\",\n"
                + "         \"type\":\"general\",\n"
                + "         \"properties\":{\n"
                + "            \"value1\":\"Need to fetch this value\"\n"
                + "         }\n"
                + "      },\n"
                + "      {\n"
                + "         \"id\":\"341256\",\n"
                + "         \"type\":\"general\",\n"
                + "         \"properties\":{\n"
                + "            \"value1\":\"1\",\n"
                + "            \"value2\":\"2\"\n"
                + "         }\n"
                + "      }\n"
                + "   ]\n"
                + "}";

        final JSONObject jsonObject = new JSONObject(jsonData);
        final JSONArray machines = jsonObject.getJSONArray("machines");
        for (int i = 0; i < machines.length(); i++) {
            final JSONObject machine = machines.getJSONObject(i);
            final JSONObject properties = machine.getJSONObject("properties");
            System.out.println(properties.get("value1"));
        }
    }

Result:

1

Need to fetch this value

1