Android java JSON parsing 'null' as output -

we have been using this code in our application fetch data online database, whatever tried, keeps saying "null" output album , duration. small detail, since beginning developers, don't know lot json. has got suggestions?

package com.example.androidhive;  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.intent; import android.os.asynctask; import android.os.bundle; import android.text.html; import android.util.log; import android.widget.textview;  import com.example.androidhive.helper.alertdialogmanager; import com.example.androidhive.helper.connectiondetector; import com.example.androidhive.helper.jsonparser;  public class singletrackactivity extends activity {     // connection detector     connectiondetector cd;      // alert dialog manager     alertdialogmanager alert = new alertdialogmanager();      // progress dialog     private progressdialog pdialog;      // creating json parser object     jsonparser jsonparser = new jsonparser();      // tracks jsonarray     jsonarray albums = null;      // album id     string album_id = null;     string song_id = null;      string album_name, song_name, duration;      // single song json url     // parameters album, song     private static final string url_song = "http://api.androidhive.info/songs/track.php";      // json node names     private static final string tag_name = "name";     private static final string tag_duration = "duration";     private static final string tag_album = "album";      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_single_track);          cd = new connectiondetector(getapplicationcontext());          // check if internet present         if (!cd.isconnectingtointernet()) {             // internet connection not present             alert.showalertdialog(singletrackactivity.this, "internet connection error",                     "please connect working internet connection", false);             // stop executing code return             return;         }          // album id, song id         intent = getintent();         album_id = i.getstringextra("album_id");         song_id = i.getstringextra("song_id");          // calling background thread         new loadsingletrack().execute();     }      /**      * background async task single song information      * */     class loadsingletrack extends asynctask<string, string, string> {          /**          * before starting background thread show progress dialog          * */         @override         protected void onpreexecute() {             super.onpreexecute();             pdialog = new progressdialog(singletrackactivity.this);             pdialog.setmessage("loading song ...");             pdialog.setindeterminate(false);             pdialog.setcancelable(false);             pdialog.show();         }          /**          * getting song json , parsing          * */         protected string doinbackground(string... args) {             // building parameters             list<namevaluepair> params = new arraylist<namevaluepair>();              // post album id, song id parameters             params.add(new basicnamevaluepair("album", album_id));             params.add(new basicnamevaluepair("song", song_id));              // getting json string url             string json = jsonparser.makehttprequest(url_song, "get",                     params);              // check log cat json reponse             log.d("single track json: ", json);              try {                 jsonobject jobj = new jsonobject(json);                 if(jobj != null){                     song_name = jobj.getstring(tag_name);                     album_name = jobj.getstring(tag_album);                     duration = jobj.getstring(tag_duration);                                     }                         } catch (jsonexception e) {                 e.printstacktrace();             }              return null;         }          /**          * after completing background task dismiss progress dialog          * **/         protected void onpostexecute(string file_url) {             // dismiss dialog after getting song information             pdialog.dismiss();              // updating ui background thread             runonuithread(new runnable() {                 public void run() {                      textview txt_song_name = (textview) findviewbyid(r.id.song_title);                     textview txt_album_name = (textview) findviewbyid(r.id.album_name);                     textview txt_duration = (textview) findviewbyid(r.id.duration);                      // displaying song data in view                     txt_song_name.settext(song_name);                     txt_album_name.settext(html.fromhtml("<b>album:</b> " + album_name));                     txt_duration.settext(html.fromhtml("<b>duration:</b> " + duration));                      // change activity title song title                     settitle(song_name);                 }             });          }      } } 

looking @ tutorial link to, appears request like:

http://api.androidhive.info/songs/track.php?album=3&song=1 

and response is:

{"id":1,"name":"born die","duration":"4:46","album_id":"3","album":"lana del rey - born die"} 

given ... there's nothing wrong json parsing.

you need verify "album" (album_id) , "song" (song_id) parameters think when get.

the php script doesn't return data if empty (e.g. http://api.androidhive.info/songs/track.php?album=&song=) , returns no album if aren't recognizes. appear that's occurring , therefore output of program null values.