android - displaying jsonarray data on textview -

im trying make android application school. want happen first, when user loggedin username saved in sharedpreferences second, using sharedpreference retrieve user info in database. third, parse data , display info in textviews. php file

       <?php      /*     our "config.inc.php" file connects database every time include or require     within php script.  since want script add new user our db,     talking our database, , therefore,     let's require connection happen:     */     require("config.inc.php");      if (!empty($_post)) {          //initial query         $query = "select * userinfo username = :user";          $query_params = array(':user' = > $_post['username']);          //execute query         try {             $stmt = $db - > prepare($query);             $result = $stmt - > execute($query_params);         } catch (pdoexception $ex) {             $response["success"] = 0;             $response["message"] = "database error!";             die(json_encode($response));         }          // finally, can retrieve of found rows array using fetchall          $rows = $stmt - > fetchall();          if ($rows) {             $response["success"] = 1;             $response["message"] = "post available!";             $response["users"] = array();              foreach($rows $row) {                 $user = array();                 $user["username"] = $row["username"];                 $user["firstname"] = $row["firstname"];                 $user["middlename"] = $row["middlename"];                 $user["lastname"] = $row["lastname"];                 $user["course"] = $row["course"];                  //update our repsonse json data                 array_push($response["users"], $user);             }              // echoing json response             echo json_encode($response);          } else {             $response["success"] = 0;             $response["message"] = "no user available!";             die(json_encode($response));         }     } else {}             ?> 

and java code

    import java.util.arraylist;     import java.util.list;     import org.apache.http.namevaluepair;     import org.apache.http.message.basicnamevaluepair;     import org.json.jsonarray;     import org.json.jsonexception;     import org.json.jsonobject;     import android.app.activity;     import android.app.progressdialog;     import android.content.sharedpreferences;     import android.os.asynctask;     import android.os.bundle;     import android.preference.preferencemanager;     import android.util.log;     import android.widget.textview;      public class profileactivity extends activity {     // xml labels      textview txtfname;     textview txtmname;     textview txtlname;      // progress dialog     private progressdialog pdialog;      // creating json parser object     jsonparser jsonparser = new jsonparser();      // profile json object     jsonarray user;     jsonobject hay;     // profile json url     private static final string profile_url =         "http://10.0.2.2/webservice1/userprofile.php";      // json node names     private static final string tag_profile = "user";     // private static final string tag_id = "id";     private static final string tag_username = "username";     private static final string tag_firstname = "firstname";     private static final string tag_middlename = "middlename";     private static final string tag_lastname = "lastname";       @override     public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_profile);       txtfname = (textview) findviewbyid(r.id.fname);     txtmname = (textview) findviewbyid(r.id.mname);     txtlname = (textview) findviewbyid(r.id.lname);      // loading profile in background thread     new loadprofile().execute();     }      /**     * background async task load profile making http request     * */     class loadprofile extends asynctask<string, string, string> {      /**      * before starting background thread show progress dialog      * */      public void test(){                  /**                  * updating parsed json data listview                  * */                 // storing each json item in variable                 try {                     string firstname = hay.getstring(tag_firstname);                     string middlename = hay.getstring(tag_middlename);                     string lastname = hay.getstring(tag_lastname);                      // displaying data in textview                      txtemail.settext("email: " + firstname);                     txtmobile.settext("mobile: " + middlename);                     txtaddress.settext("add: " + lastname);                  } catch (jsonexception e) {                     // todo auto-generated catch block                     e.printstacktrace();                 }      }      @override     protected void onpreexecute() {         super.onpreexecute();         pdialog = new progressdialog(profileactivity.this);         pdialog.setmessage("loading profile ...");         pdialog.setindeterminate(false);         pdialog.setcancelable(false);         pdialog.show();     }     /**      * getting profile json      * */     protected string doinbackground(string... args) {         // building parameters          sharedpreferences sp = preferencemanager.getdefaultsharedpreferences(profileactivity.this);         string post_username = sp.getstring("username", "anon");         list<namevaluepair> params = new arraylist<namevaluepair>();         params.add(new basicnamevaluepair("username", post_username));         // getting json string url         jsonobject json = jsonparser.makehttprequest(profile_url, "post",                 params);          // check log cat json reponse         log.d("profile json: ", json.tostring());          try {             // profile json object             user = json.getjsonarray(tag_profile);         } catch (jsonexception e) {             e.printstacktrace();         }          return null;     }      /**      * after completing background task dismiss progress dialog      * **/     protected void onpostexecute(string file_url) {         // dismiss dialog after getting products         pdialog.dismiss();         // updating ui background thread         test();      }  }     } 

im getting nullpointer exception profileactivity$loadprofile.test please me im beginner

you have not initialized hey. have declaired hey. if data in json assign hey = json in postexecute or pass json directly test , use there.