GSON - remove JSON data from JSON object

Question

I'm looking to remove part of a JSON object, at the moment I only seem to be able to return the whole object.

JSON format:

{"blobJson":"{\"sensorID\":\"111122\",\"width\":32,\"height\":31,\"frameData\":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]}","deviceMfg":2,"eventCode":101,"sensorClass":1,"sensorUUID":"111122","timeStamp":1.53907307310099994E18,"uID":"111122_1_2"}

I'm looking to remove the [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0] part of the JSON.

At the moment I'm using the following code:

    JsonParser jp = new JsonParser(); //from gson
    JsonElement root = jp.parse(new InputStreamReader((InputStream) request.getContent())); 
    JsonObject rootobj = root.getAsJsonObject();
    System.out.println(rootobj);

This is outputting the following JSON:

{"blobJson":"","deviceMfg":-1,"eventCode":-1,"sensorClass":-1,"sensorUUID":"","timeStamp":0.0,"uID":"_-1_-1"}

Answer 1

String stringifyRequest="{"blobJson":"{\"sensorID\":\"111122\",\"width\":32,\"height\":31,\"frameData\":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]}","deviceMfg":2,"eventCode":101,"sensorClass":1,"sensorUUID":"111122","timeStamp":1.53907307310099994E18,"uID":"111122_1_2"}";

 final ObjectMapper mapper = new ObjectMapper();
        "Yourpojoclass" investmentResponse = mapper.readValue(stringifyRequest, "Yourpojoclass".class);

here "Yourpojoclass" would be your class which consists string field parameter:

Now set your frameData value null and make your pojo class @JsonInclude(value=Include.NON_NULL)

and then convert it again in json.

Answer 2

If you want to remove the framedata key and value from the string. You can use the org.json.JSONObject as shown below:

JSONObject jo1 = new JSONObject("{\"blobJson\":{\"sensorID\":\"111122\",\"width\":32,\"height\":31,\"frameData\":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]},\"deviceMfg\":2,\"eventCode\":101,\"sensorClass\":1,\"sensorUUID\":\"111122\",\"timeStamp\":1.53907307310099994E18,\"uID\":\"111122_1_2\"}");
jo1.getJSONObject("blobJson").remove("frameData");

If you want to retain the key framedata but want only the value to be replace with [] then do the following:

JSONObject jo1 = new JSONObject("{\"blobJson\":{\"sensorID\":\"111122\",\"width\":32,\"height\":31,\"frameData\":[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]},\"deviceMfg\":2,\"eventCode\":101,\"sensorClass\":1,\"sensorUUID\":\"111122\",\"timeStamp\":1.53907307310099994E18,\"uID\":\"111122_1_2\"}");
jo1.getJSONObject("blobJson").put("frameData", "[]");

You can use ObjectMapper from com.fasterxml.jackson.databind but then you require the corresponding class also with all the member variables corresponding to the json keys. In the above approach you can directly manipulate the Json String.