Writing to a JSON file

Question

I am working on an android application using a json file in order to store data used by the application. I have a Json file in the asset folder, including one object "plants". In the Dashboard.java file, I would like to add an object to the json file. I tried this by using the put() function, but I doesnt seem to write in the actual file. Dashboard.java :

            String name = intent.getStringExtra(AddAPlant.EXTRA_TEXT1);
            String description = intent.getStringExtra(AddAPlant.EXTRA_TEXT2);
            String url = intent.getStringExtra(AddAPlant.EXTRA_TEXT3);

            JSONObject jsonObj= new JSONObject();

            try {
                jsonObj.put("name", name);
                jsonObj.put("description", description);
                jsonObj.put("cameralink", url);

            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            plantArray = new JSONArray();
            plantArray.put(jsonObj);

Json file located in asset folder :

{
  "plants": [
    {
      "name": "Pepper",
      "decription": "This is a big plant",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam1-snapshots/gallery-images/latest.png"
    },
    {
      "name": "Tomatoe",
      "decription": "This is a big plant",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam2-snapshots/gallery-images/latest.png"
    },
    {
      "name": "Small Tomato",
      "decription": "It needs a lot of water",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam3-snapshots/gallery-images/latest.png"
    }
  ]
}

Desired output :

{
  "plants": [
    {
      "name": "Pepper",
      "decription": "This is a big plant",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam1-snapshots/gallery-images/latest.png"
    },
    {
      "name": "Tomatoe",
      "decription": "This is a big plant",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam2-snapshots/gallery-images/latest.png"
    },
    {
      "name": "Small Tomato",
      "decription": "It needs a lot of water",
      "CameraLink": "https://messir.uni.lu/bicslab/blab-cam3-snapshots/gallery-images/latest.png"
    }, 
    {
      "name": name,
      "decription": description,
      "CameraLink": url

  ]
}

You first need to instantiate `plantArray` by parsing its content from the json file. You can find instructions on how do it in the answers to this question: [How to parse JSON array from file?](https://stackoverflow.com/questions/39689507/how-to-parse-json-array-from-file) — razumichin, Apr 26 '20 at 10:57

score 1 · Accepted Answer · answered Apr 26 '20 at 11:49

i do not think it is possible to write to /assets at run time check this answer

try using app specific files docs

To make changes to JSON. Read from file (String data) and initialize a JSONobject.

JSONObject obj = new JSONObject("string from your file")

  JSONObject jsonObject = new JSONObject("data from file");
  JSONArray jsonArray =  jsonObject.getJSONArray("plants");

  JSONObject jsonObj = new JSONObject();
  jsonObj.put("name", name);
  jsonObj.put("description", description);
  jsonObj.put("cameralink", url);

  jsonArray = jsonArray.put(jsonObj);
  jsonObject = jsonObject.put("plants", jsonArray);

  //convert json object to string
  String data = jsonObject.toString();

  FileOutputStream fout = context.openFileOutput(filename, Context.MODE_PRIVATE);
  fout.write(data.getBytes());

Writing to a JSON file

1 Answers1