Android: Best practice for handling JSON data

Question

I've been researching how to query JSON data from a server and parse it for use in my application. However, I've found a number of different ways to do the same thing. I realize there are different JSON parsers out there, so let's assume I'm sticking with the standard one. The main question I have has to do with the server requests. Here is my current code for my MapActivity

private class DownloadJSON extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Create a Progress Dialog
        mProgressDialog = new ProgressDialog(MapActivity.this);
        mProgressDialog.setTitle("Downloading Data");
        mProgressDialog.setMessage("Loading...");
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
        // Create an array
        arraylist = new ArrayList<HashMap<String, String>>();

        try {
            // Retrieve JSON Objects from the given URL address
            jsonarray = JSONFunctions.getJSONfromURL("myurl");

            for (int i = 0; i < jsonarray.length(); i++) {
                HashMap<String, String> map = new HashMap<String, String>();
                JSONObject obj = jsonarray.getJSONObject(i);

                // Retrieve JSON Objects
                map.put("id",  String.valueOf(i));
                map.put("name", obj.getString("name"));

                // Set the JSON Objects into the array
                arraylist.add(map);
            }

        } catch (JSONException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void args) {
        // Do something with data
        mProgressDialog.dismiss();
    }
}

If the structure of my JSON data looks weird, it's because it's stored in an unnamed array so I don't have to create an object first. Anyway... I essentially based this off of this tutorial. However, they have soooo much more code. Is that all really necessary? I didn't think so. I searched around more and found other examples that used half the code and essentially did the same thing. So my question, as a beginning Android programmer, is what is the best practice for handling JSON data? Thanks!

Example of JSON file:

[
    {
        "name": "test",
        "lat": "42.01108",
        "long": "93.679196"
    },
    {
        "name": "test",
        "lat": "42.01108",
        "long": "93.679196"
    }
]

Answer 1

@leerob Hello, at one time I found myself in a dilemma where you are, but lately I have used base classes that brings Android to handle json and is pretty good, a good practice I recommend you is to declare constants for the keys of json, I share an example:

 public void insertMovieTypeFromJson(String movieTypeJsonStr) throws JSONException {
            final String ID = "id";
            final String TYPE = "type";
            final String DESCRIPTION = "description";

            if (movieTypeJsonStr == null)
                    return;

            try {
                    JSONArray movieTypeArrayJson = new JSONArray(movieTypeJsonStr);

                    Vector<ContentValues> cVVector = new Vector<>(movieTypeArrayJson.length());

                    for (int i = 0; i < movieTypeArrayJson.length(); i++) {

                            long id;
                            String type;
                            String description;

                            JSONObject movie = movieTypeArrayJson.getJSONObject(i);

                            id = movie.getLong(ID);
                            type = movie.getString(TYPE);
                            description = movie.getString(DESCRIPTION);

                            ContentValues movieTypeValues = new ContentValues();

                            movieTypeValues.put(MovieContract.MovieTypeEntry._ID, id);
                            movieTypeValues.put(MovieContract.MovieTypeEntry.COLUMN_TYPE, type);
                            movieTypeValues.put(MovieContract.MovieTypeEntry.COLUMN_DESCRIPTION, description);
                            cVVector.add(movieTypeValues);
                    }

                    int inserted = 0;

                    if (cVVector.size() > 0) {
                            ContentValues[] cvArray = new ContentValues[cVVector.size()];
                            cVVector.toArray(cvArray);
                            inserted = getContext().getContentResolver().bulkInsert(MovieContract.MovieTypeEntry.CONTENT_URI, cvArray);
                    }

                    Log.d(LOG_TAG, "MovieTask Complete. " + inserted + " MovieType Inserted");

            } catch (JSONException e) {
                    Log.e(LOG_TAG, e.getMessage(), e);
                    e.printStackTrace();
            }
    }

Json:

[
    {
        "id": "1",
        "type": "Action & Adventure",
        "description": "Action & Adventure"
    },
    {
        "id": "2",
        "type": "Animation",
        "description": "Animation"
    },
    {
        "id": "3",
        "type": "Comedy",
        "description": "Comedy"
    },
    {
        "id": "4",
        "type": "Terror",
        "description": "Terror"
    }
]

Answer 2

Try this...

private class TestJSONParsing extends AsyncTask<JSONArray, Void, JSONArray>
{
    ArrayList<HashMap<String, String>> arraylist;
    HashMap<String, String> map;

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
        mProgressDialog = new ProgressDialog(MapActivity.this);
        mProgressDialog.setTitle("Downloading Data");
        mProgressDialog.setMessage("Loading...");
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.show();

    }

    @Override
    protected JSONArray doInBackground(JSONArray... params)
    {
        return JSONFunctions.getJSONfromURL("myurl");

    }

    @Override
    protected void onPostExecute(JSONArray resultArray)
    {
        super.onPostExecute(resultArray);
        mProgressDialog.dismiss();
        if (null != resultArray)
        {
            int resultLength = resultArray.length();
            if (resultLength > 0)
            {
                try
                {
                    for (int i = 0; i < resultLength; i++)
                    {
                        JSONObject jsonObject = resultArray
                                .getJSONObject(i);
                        map.put("id", String.valueOf(i));
                        map.put("name", jsonObject.getString("name"));
                        arraylist.add(map);
                    }
                } catch (Exception e)
                {
                    // TODO: handle exception
                    e.printStackTrace();
                }

                if (arraylist.size() > 0)
                {
                    SimpleAdapter adapter = new SimpleAdapter(
                            MapActivity.this, arraylist,
                            R.layout.your_simple_row, new String[]
                            { "id", "name" }, new int[]
                            { R.id.nameId, R.id.name });
                    // bind adapter to your components
                    listView.setAdapter(adapter);
                }
            }
        } else
        {
            Toast.makeText(getApplicationContext(), "No data",
                    Toast.LENGTH_SHORT).show();
        }

    }

}