Progress dialog android json

Question

I have a problem wih my progressdialog, my app searches for the data from json and after that the dialog comes, but I want it at this time while he collects the data. where is my mistake?

There is the edited code logcat( FATAL EXCEPTION: main java.lang.NullPointerException) JSON ([{"name":"Test"}]) edit:

public class MainActivity extends ListActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    new TheTask().execute();
}
class TheTask extends AsyncTask<Void, Void, JSONObject> {
    InputStream is = null;
    String result = "";
    JSONObject jArray = null;

    ProgressDialog pd;

    @Override
    protected void onPostExecute(JSONObject result) {
        super.onPostExecute(result);
        pd.dismiss();
        JSONObject jObject = result;
        try {
            String aJsonString = jObject.getString("name");
        } catch (JSONException e) {
            e.printStackTrace();
        }
        setListAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, (List<String>) result));
        // parse and set List adapter here
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd = ProgressDialog.show(MainActivity.this, "dialog title",
                "dialog message", true);
    }

    @Override
    protected JSONObject doInBackground(Void... arg0) {
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("***");
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

        } catch (Exception e) {
            Log.e("log_tag", "Error in http connection " + e.toString());
        }

        // Convert response to string
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();
        } catch (Exception e) {
            Log.e("log_tag", "Error converting result " + e.toString());
        }

        try {

            jArray = new JSONObject(result);
        } catch (JSONException e) {
            Log.e("log_tag", "Error parsing data " + e.toString());
        }

        return jArray;
    }
}

Raghunandan · Accepted Answer · 2014-01-30T09:49:12.300

Thread.sleep(50);

You are calling sleep on the ui thread which blocks it. Remove it.

Use AsyncTask instead of a Thread.

http://developer.android.com/reference/android/os/AsyncTask.html

Show progress dialog in onPreExecute. Do your http request in doInbackground. Dismiss dialog in onPostExecute and update ui accordingly.

To invoke

 new TheTask().execute();

Then

 class TheTask extends AsyncTask<Void, Void, Void>    {

        ProgressDialog pd;

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            progress.dismiss();

        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
             progress = ProgressDialog.show(MainActivity.this, "dialog title",
                            "dialog message", true);
        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // http request
            return null;
        }   
    }

Edit:

public class MainActivity extends ListActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    new TheTask().execute();
    }
class TheTask extends AsyncTask<Void, Void, JSONObject> {
    InputStream is = null;
    String result = "";
    JSONObject jArray = null;

    ProgressDialog pd;

    @Override
    protected void onPostExecute(JSONObject result) {
        super.onPostExecute(result);
        pd.dismiss();
        // parse and set List adapter here
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd = ProgressDialog.show(MainActivity.this, "dialog title",
                "dialog message", true);
    }

    @Override
    protected JSONObject doInBackground(Void... arg0) {
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("******");
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

        } catch (Exception e) {
            Log.e("log_tag", "Error in http connection " + e.toString());
        }

        // Convert response to string
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();
        } catch (Exception e) {
            Log.e("log_tag", "Error converting result " + e.toString());
        }

        try {

            jArray = new JSONObject(result);
        } catch (JSONException e) {
            Log.e("log_tag", "Error parsing data " + e.toString());
        }

        return jArray;
    }
}
}

Edit2:

   class TheTask extends AsyncTask<Void, Void, JSONArray> {
    InputStream is = null;
    String result = "";
    JSONArray jArray = null;

    ProgressDialog pd;

    @Override
    protected void onPostExecute(JSONArray result) {
        super.onPostExecute(result);
        pd.dismiss();
        ArrayList<String> list= new ArrayList<String>();
        try
        {
        for(int i=0;i<result.length();i++)
        {

            JSONObject jb = result.getJSONObject(i) ;
            String name = jb.getString("name");
            list.add(name);
        }
        }catch(Exception e)
        {
            e.printStackTrace();
        }
        setListAdapter(new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, list));
    }
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pd = ProgressDialog.show(MainActivity.this, "dialog title",
                "dialog message", true);
    }

    @Override
    protected JSONArray doInBackground(Void... arg0) {
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("******");
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

        } catch (Exception e) {
            Log.e("log_tag", "Error in http connection " + e.toString());
        }

        // Convert response to string
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();
        } catch (Exception e) {
            Log.e("log_tag", "Error converting result " + e.toString());
        }

        try {

            jArray = new JSONArray(result);
        } catch (JSONException e) {
            Log.e("log_tag", "Error parsing data " + e.toString());
        }

        return jArray;
    }
}
}

make asynctask an inner class of activity class also pot your updated code — Raghunandan, Jan 29 '14 at 18:40
http://pastebin.com/MEvZVMZE there I want to parse the Json but then my app quits — user3241084, Jan 30 '14 at 09:20
@user3241084 you need to post you code here. I am not going to open a link and look at your code and you need to post the stacktrace as well to indicate the crash — Raghunandan, Jan 30 '14 at 09:22
@user3241084 edit your post and add the code. Code should ne added in comments and post the logcat also result is a JSONObject not a list or string array what you are doing makes no sense — Raghunandan, Jan 30 '14 at 09:25
@user3241084 check edit2 it will work. if oyu have posted the json right — Raghunandan, Jan 30 '14 at 09:49
is there also a way to safe the json data at the phone that you can see the data also if your phone is offline? — user3241084, Jan 30 '14 at 10:04
@user3241084 yes its called caching. do ask a new question and do accept this answer by clicking on the tick next to the answer. — Raghunandan, Jan 30 '14 at 10:05
http://stackoverflow.com/questions/21460461/json-data-available-offline there its going on ;) — user3241084, Jan 30 '14 at 15:26

score 0 · Answer 2 · edited May 23 '17 at 12:03

0

You call Thread.sleep(50) on the UI Thread so the UI freezes until its done. Move your operations to an AsyncTask and sleep() in doInBackground(). Put all of your network code in doInBackground() also.

You can use AsyncTasks other methods to update the UI.

See this answer for an example of AsyncTask if you are unfamiliar

AsyncTask Docs

edited May 23 '17 at 12:03

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answered Jan 29 '14 at 17:58

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Progress dialog android json

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