Question

I have an IntentService that does network action (HTTP POST) but it shows a NetworkOnMainThreadException. IF I am right, IntentService will be running on a separate thread. Can anybody tell why this exception is thrown? my code is:

public class UpdateService extends IntentService {
public static final int UPDATE_PROGRESS = 8344;
BroadcastReceiver broadcastReceiver;
public UpdateService() {
    super("UpdateService");
}
@Override
protected void onHandleIntent(Intent intent) {

        if (broadcastReceiver == null) {

            broadcastReceiver = new BroadcastReceiver() {

                @Override
                public void onReceive(Context context, Intent intent) {

                    Bundle extras = intent.getExtras();

                    NetworkInfo info = (NetworkInfo) extras.getParcelable("networkInfo");

                    State state = info.getState();
                    if (state == State.CONNECTED) {

                        onNetworkUp();

                    } else {

                    }
                }
            };

            final IntentFilter intentFilter = new IntentFilter();
            intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
            registerReceiver(broadcastReceiver, intentFilter);
        }
}

@Override
public void onDestroy(){
    unregisterReceiver(broadcastReceiver);
    }

void onNetworkUp(){
    String aDataRow = "";
    try {
        File myFile = new File( Environment.getExternalStorageDirectory().getPath() + "/myFile.txt");
        FileReader fr = new FileReader(myFile);
        BufferedReader myReader = new BufferedReader(fr);   
        while ((aDataRow = myReader.readLine()) != null) 
        updateLyne(aDataRow); //
        fr.close();
    } catch (Exception e) {
        Log.e("onNetworkUp",e.toString());
    }   


    void updateLyne(String aDataRow){
    JSONParser jsonParser = new JSONParser();
    String[] words = aDataRow.split(" ");
    pid = words[1];
    String rtime = aDataRow;
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair(TAG_PID, pid));
    params.add(new BasicNameValuePair(TAG_TIME, rtime));

    JSONObject json = null;
    if (words[0].equalsIgnoreCase("cancel")){
        json = jsonParser.makeHttpRequest(url_cancel, "POST", params);                  
    }
    else{
        Log.d("empty","file empty!!");
    }

    try {
        int success = json.getInt("success");

        if (success == 1) {
            delLine(aDataRow); // delete the line
        } else {
            Log.d("pid="+pid+" not on board", "failed in deleting");
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

}
}

the JSONParser.java is given below

    public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

// function get json from url
public JSONObject makeHttpRequest(String url, String method,
        List<NameValuePair> params) {

    // Making HTTP request
    try {

        // check for request method
        if(method == "POST"){

            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();
        }

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    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();
        json = sb.toString();
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }

    // return JSON String
    return jObj;

}
    }

Answer 1

The problem is that you’re not running network request in onHandleIntent(), you’re just creating an instance of BroadcastReceiver and registering it. The actual network request won’t run there. It will run when the BroadcastReceiver receives a message, which happens on UI thread. A right scheme here would be to create your BroadcastReceiver somewhere else, and when a message is received, start an IntentService, which executes a network call inside onHandleIntent() – then indeed it will run on a worker thread. Hope this helps.