android - JSON exception to parse photo_refrence from Google places api -

i have made json android application, show reference of photos, in list view, gives me error code is\

package com.example.jsonapp; import java.util.arraylist; import java.util.hashmap; import org.json.jsonarray; import org.json.jsonexception; import org.json.jsonobject; import android.app.activity; import android.app.listactivity; import android.app.progressdialog; import android.content.context; import android.os.asynctask; import android.os.bundle; import android.view.menu; import android.widget.listadapter; import android.widget.simpleadapter; 

public class mainactivity extends listactivity { // url make request private static string url = "https://maps.googleapis.com/maps/api/place/nearbysearch /json?location=mylatandlong&radius=5000&types=restaurant&sensor=false&key=myownkey";

// json node names private static final string tag_results = "results"; private static final string tag_photos = "photos"; private static final string tag_refrence = "photo_reference";  jsonarray results = null; jsonarray photos = null;  context c;    // progress dialog progressdialog pdialog; arraylist<hashmap<string, string>> contactlist;   @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);        new laodphotos().execute(tag_refrence);      //listview lv = getlistview();  }//the end of on create  public class laodphotos extends asynctask<string, string, string>{      @override     protected void onpreexecute() {         super.onpreexecute();         pdialog = new progressdialog(mainactivity.this);         pdialog.setmessage("loading profile ...");         pdialog.setindeterminate(false);         pdialog.setcancelable(false);         pdialog.show();     }     @override     protected string doinbackground(string... arg0) {         contactlist = new arraylist<hashmap<string, string>>();         jsonparser jparser = new jsonparser();         jsonobject json = jparser.getjsonfromurl(url);         try{             results = json.getjsonarray(tag_results);             photos = json.getjsonarray(tag_photos);              for(int i=0; i<results.length(); i++){                 jsonobject c = results.getjsonobject(i);                 if(c != null){                     for(int j=0; j<photos.length(); j++){                         jsonobject pc = photos.getjsonobject(j);                         string photo = pc.getstring(tag_refrence);                          // creating new hashmap                         hashmap<string, string> map = new hashmap<string, string>();                          map.put(tag_refrence, photo);                          contactlist.add(map);                     }                 }                }          }catch(jsonexception e){             e.printstacktrace();         }         return null;     }      @override     protected void onpostexecute(string file_url) {         // dismiss dialog after getting products         pdialog.dismiss();         // updating ui background thread         runonuithread(new runnable() {             public void run() {                  listadapter adapter = new simpleadapter(c, contactlist, r.layout.list_item,                         new string[]{tag_refrence}, new int[]{r.id.photoref});                  setlistadapter(adapter);              }//end of run method         });//end of runonuithread     }//end of onpost method     }   @override public boolean oncreateoptionsmenu(menu menu) {     // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.main, menu);     return true; } 

}

the log cat\ e/androidruntime(23042): java.lang.nullpointerexception e/androidruntime(23042): @ android.widget.simpleadapter.(simpleadapter.java:85)

would 1 me know how make succeed, want have photo_reference able show image, first need know how have photo_reference?!

you forget initialize c context instance activity context before passing simpleadapter.so pass activity context adapter as:

listadapter adapter = new simpleadapter(mainactivity.this,                                       contactlist, r.layout.list_item,                                       new string[]{tag_refrence},                                        new int[]{r.id.photoref});   mainactivity.this.setlistadapter(adapter); 

and onpostexecute method run on ui thread no need use runonuithread updating ui elements form onpostexecute