JSON Data stored to SQLite

Question

I am following this to store JSON parsed data into SQLite Database, but whenever i use my app offline not getting stored data into ListView.

Is there anything left to implement in my existing code ?

MainActivity.java:-

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        databaseHelper=new CategoryHelper(MainActivity.this);
        contactList = new ArrayList<HashMap<String, String>>();

        ListView lv = getListView();

        // Listview on item click listener
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {


            }
        });

        // Calling async task to get json
        new GetContacts().execute();
    }

    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Please wait...");
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // Creating service handler class instance
            ServiceHandler sh = new ServiceHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);

            Log.d("Response: ", "> " + jsonStr);

            if (jsonStr != null) {
                try {
                    JSONObject jsonObj = new JSONObject(jsonStr);

                    // Getting JSON Array node
                    contacts = jsonObj.getJSONArray(TAG_CONTACTS);

                    // looping through All Contacts
                    for (int i = 0; i < contacts.length(); i++) {
                        JSONObject c = contacts.getJSONObject(i);

                        String id = c.getString(TAG_ID);
                        String name = c.getString(TAG_NAME);

                        databaseHelper.saveCategoryRecord(id,name);

                        // tmp hashmap for single contact
                        HashMap<String, String> contact = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        contact.put(TAG_ID, id);
                        contact.put(TAG_NAME, name);

                        // adding contact to contact list
                        contactList.add(contact);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } else {
                Log.e("ServiceHandler", "Couldn't get any data from the url");
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            /**
             * Updating parsed JSON data into ListView
             * */
            ListAdapter adapter = new SimpleAdapter(
                    MainActivity.this, contactList,
                    R.layout.list_item, new String[] { TAG_NAME }, new int[] { R.id.name });

            setListAdapter(adapter);
        }

    }

When offline you want to get the data from sqlite? if yes Where did you wrote the code for retrieving the data from sqlite? — Vamshi, Feb 26 '14 at 09:14
@Vamshi actually i am new and don't know how to retrieve code from sqlite to show in a List in onCreate(), will you help me? — JESUS, Feb 26 '14 at 09:20

score 0 · Answer 1 · answered Feb 26 '14 at 09:15

I don't know what that ServiceHandler thing is, but I'm guessing the call to makeServiceCall() returns null when you're offline. This means you aren't populating the contactList, which means it's empty when you're creating the ListAdapter.

I'm guessing what you want to do, is add an else clause to if (jsonStr != null) that populates contactList with records from your DB. How to do this depends on the implementation details of CategoryHelper.

score 0 · Answer 2 · answered Feb 26 '14 at 10:08

Using shared preference would be a better approach for that. Follow these steps:

search and download GSON library. This will simplify our task for saving and retrieving JSON to/from shared preferences and let your app use the GSON library

example:

SharedPreferences prefs = getSharedPreferences("mySharedPreferenceKey");
Editor editor = prefs.edit();
Gson gson = new Gson();

//convert your object to string and save it to shared preference
ArrayList<Integer> myIntArrs = new ArrayList<Integer>();
editor.putString("myJSONKey", new Gson().toJson(myIntArrs)).commit();

//get your json string from shared preferences
public final Type ARRAYLIST_INTEGER = new TypeToken<ArrayList<Integer>>(){}.getType(); 
ArrayList<Integer> intArrs = gson.fromJson(prefs.getString("myJSONKey", "{}"), ARRAYLIST_INTEGER);

//do something with your intArrs

Hope this helps!

i tried many times, but not solved, can you show me the way by making changes in my existing code ? — JESUS, Apr 11 '14 at 10:04

JSON Data stored to SQLite

2 Answers2