how to retrive large data form webservice [on hold]

My Android application need to retreive large data from webserver database via webservice in background process. and save data in local sqlite database.

Problem that I am facing is that my app crashes when someone is viewing the app and at the same time if updation of data is also going on.

It seems that I cannot INSERT data while app is retrieving data from sqlite database.

So, I need functionality like in whatsapp where I can send messages to other users and still messages from different users come which means data is getting inserted in local db in the background. Please help.

 package com.ht.scd.scd.helper;

    import android.util.Log;

    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import java.io.OutputStreamWriter;
    import java.net.HttpURLConnection;
    import java.net.URL;
    import java.net.URLEncoder;
    import java.util.HashMap;
    import java.util.Map;

    import javax.net.ssl.HttpsURLConnection;

    public class ServiceHandler {

        //static String    response = null;
        public final static int GETRequest       = 1;
        public final static int POSTRequest      = 2;

        public ServiceHandler() {

        }

        /*
         * Making service call
         * 
         * @url - url to make request
         * 
         * @method - http request method
         */
        public String makeServiceCall(String url, int method) {
            return this.makeServiceCall(url, method, null);
        }

        /*
         * Making service call
         * 
         * @url - url to make request
         * 
         * @method - http request method
         * 
         * @params - http request params
         */
        public String makeServiceCall(String urladdress, int requestmethod, HashMap<String, String> params) {

            URL url;
            String responseResult = "";
            try {
                url = new URL(urladdress);
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(15001);
                conn.setConnectTimeout(15001);
                conn.setDoInput(true);
                conn.setDoOutput(true);
                if (requestmethod == POSTRequest) {
                    conn.setRequestMethod("POST");
                } else if (requestmethod == GETRequest) {
                    conn.setRequestMethod("GET");
                }
                if (params != null) {
                    OutputStream ostream = conn.getOutputStream();
                    BufferedWriter writer = new BufferedWriter(
                            new OutputStreamWriter(ostream, "UTF-8"));
                    StringBuilder requestresult = new StringBuilder();
                    boolean first = true;
                    for (Map.Entry<String, String> entry : params.entrySet()) {
                        if (first)
                            first = false;
                        else
                            requestresult.append("&");
                        requestresult.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
                        requestresult.append("=");
                        requestresult.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
                    }
                    writer.write(requestresult.toString());

                    writer.flush();
                    writer.close();
                    ostream.close();
                }
                int reqresponseCode = conn.getResponseCode();

                if (reqresponseCode == HttpsURLConnection.HTTP_OK) {
                    String line;
                    BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                    while ((line = br.readLine()) != null) {
                        responseResult += line;
                    }
                } else {
                    responseResult = "";
                }


            } catch (Exception e) {
                e.printStackTrace();
                Log.v("error in ServiceHandler",e.getMessage());
            }

            return responseResult;

        }
    }







package com.ht.scd.scd.helper;

import android.app.ProgressDialog;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.AsyncTask;
import android.util.Log;
import android.widget.Toast;

import java.util.HashMap;

public class CallWebServiceAsynTaskHelper extends AsyncTask<Void, Void, Void> {

    ProgressDialog      pDialog;
    Context      context;
    String        url;
    //List<NameValuePair> params;
    HashMap<String, String> params;

    int      int_method;              // GET or POST

    boolean      progressDialogDisplayFlag = true;
    String        msgOnDialog          = "";
    String        noInternet_msg        = "";
    boolean      isInternet;


    public interface CallWebServiceAsynTaskHelperDoneCallBackInterface {

        void CallWebServiceAsynTaskHelperDoneCallBackInterface_callBackMethod(String response);
    }

    public CallWebServiceAsynTaskHelper(Context context, String url, HashMap<String, String> params, String method,
            boolean progressDialogDisplayFlag, String msgOnDialog, String noInternet_msg) {

        this.context = context;
        this.url = url;
        this.params = params;

        this.progressDialogDisplayFlag = progressDialogDisplayFlag;

        this.msgOnDialog = msgOnDialog;
        this.noInternet_msg = noInternet_msg;

        if (method.equalsIgnoreCase("GET"))
            int_method = 1;
        else if (method.equalsIgnoreCase("POST"))
            int_method = 2;

        pDialog = new ProgressDialog(context);
    }

    String response = "";

    @Override
    protected void onPreExecute() {

        isInternet = new CheckInternet().isNetworkAvailable(context);

        if (progressDialogDisplayFlag) {
            pDialog.setMessage(msgOnDialog);
            pDialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
            pDialog.setCancelable(false);
            pDialog.show();
        }

        super.onPreExecute();
    }

    @Override
    protected Void doInBackground(Void... arg0) {
        try {

            if (isInternet) {// checkInternet

                ServiceHandler serverService = new ServiceHandler();

                if (params == null) {
                    response = serverService.makeServiceCall(url, int_method);
                } else {
                    response = serverService.makeServiceCall(url, int_method, params);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            Log.v("Complaint Error", e.toString());
        }

        return null;
    }

    @Override
    protected void onPostExecute(Void result1) {
        super.onPostExecute(result1);
        if (pDialog.isShowing())
            pDialog.dismiss();
        Log.i("Result", response+"");
        // {"msg":"success"}

        CallWebServiceAsynTaskHelperDoneCallBackInterface ifaceObj = (CallWebServiceAsynTaskHelperDoneCallBackInterface) context;
        ifaceObj.CallWebServiceAsynTaskHelperDoneCallBackInterface_callBackMethod(response);

        if (!isInternet) {
            Toast.makeText(context, noInternet_msg, Toast.LENGTH_LONG).show();

        }

    }

    public String getResponse() {
        return response;
    }



}


webservice call
 url = "http://mysocialbuy.com/webservices/all_super_coupons.php";
        callWebServiceAsynTaskHelperDoneCallBackInterface_usingFlag = "couponData";
        webserviceTask = new CallWebServiceAsynTaskHelper(this, url, null, "GET", false,
                "Please wait", "No Internet");
        webserviceTask.execute();