java - Where call cursor in Adapter Class -

i have class getallentryslistviewadapter extends baseadapter list view in pinboardactivity set array. want change likeimage if there saved entry in sqlite database. call getlike cursor in getview way:

 @override public view getview(final int position, view convertview, viewgroup parent) {      final listcell cell;     if (convertview == null) {         convertview = inflater.inflate(r.layout.get_all_entry_list_view_cell, null);          cell = new listcell();         cell.likes = (textview) convertview.findviewbyid(r.id.listviewlikes);         cell.note = (textview) convertview.findviewbyid(r.id.listviewnote);         cell.img = (imageview) convertview.findviewbyid(r.id.listviewimg);         cell.likeimage = (imageview) convertview.findviewbyid(r.id.heartimage);          convertview.settag(cell);      }     else {         cell = (listcell)convertview.gettag();     }      try {         jsonobject jsonobject = this.dataarray.getjsonobject(position);         cell.likes.settext(jsonobject.getstring("likes"));         cell.note.settext(jsonobject.getstring("note"));          string img = jsonobject.getstring("image");         string urlforimageinserver = baseurlforimage + img;          new asynctask<string, void, bitmap>() {             @override             protected bitmap doinbackground(string... params) {                 //download image                 string url = params[0];                 bitmap icon = null;                  try {                     inputstream in = new java.net.url(url).openstream();                     icon = bitmapfactory.decodestream(in);                 } catch(malformedurlexception e) {                     e.printstacktrace();                 } catch (ioexception e) {                     e.printstacktrace();                 }                  return icon;             }              @override             protected void onpostexecute(bitmap result) {                 cell.img.setimagebitmap(result);             }          }.execute(urlforimageinserver);  //cursor called --> line causes error         cursor = dbh.getlike(dbh);         cursor.movetofirst();         string markerid = pinboard.markerid;         if (cursor.movetofirst()) {             {                 if (cursor.getstring(0).equals(markerid) && integer.parseint(cursor.getstring(1))== position && integer.parseint(cursor.getstring(2)) == 1) {                     cell.likeimage.setimageresource(r.drawable.heart_filled);                 }             }             while(cursor.movetonext());         }         cursor.close();      }     catch (jsonexception e) {         e.printstacktrace();     }     return convertview;  }  public static class listcell {     private textview likes;     private textview note;     private imageview img;     public imageview likeimage;     public boolean touched;  } 

as opening pinboardactivity following error: java.lang.nullpointerexception: attempt invoke virtual method 'android.database.cursor de.mareike.cityexplorer.dbhelper.getlike(de.mareike.cityexplorer.dbhelper)' on null object reference

am calling cursor on wrong place or cause issue? way, context set way:

 public getallentryslistviewadapter(context context, cursor cursor) {     super();     cursor = cursor;     dbhelper dbh  = new dbhelper(context);    inflater=layoutinflater.from(context); }