android - Unable to access query -

i db cannot resloved error in class. @ displaylistview() function. can please me solve it. thanks

got code here http://kdehairy.com/2012/08/19/using-a-preloaded-sqlite-database-with-sqliteopenhelper/

public class prepopsqlitedbactivity extends activity {

// private static final string db_name = "hymnals";  //a practice define database field names constants     private simplecursoradapter dataadapter;  private context context;   @override   public void oncreate(bundle savedinstancestate) {      super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      //our key helper     externaldbopenhelper repo = externaldbopenhelper.getinstance( context );      sqlitedatabase  db = repo.getwritabledatabase();       displaylistview();   }   private void displaylistview() {   //all hymns fetched    *final cursor cursor = db.fetchallhymns();*    // desired columns bound   string[] columns = new string[] {            externaldbopenhelper.hymn_id,           externaldbopenhelper.hymn_name,     };    // xml defined views data bound   int[] = new int[] {     r.id.tvid,     r.id.name,    };   // create adapter using cursor pointing desired data  //as layout information      dataadapter = new simplecursoradapter(     this, r.layout.activity_main,     cursor,     columns,     to,     0);    listview listview = (listview) findviewbyid(r.id.list);  // assign adapter listview   listview.setadapter(dataadapter);     listview.setonitemclicklistener(new onitemclicklistener() {     @override    public void onitemclick(adapterview<?> listview, view view,       int position, long id) {  // cursor, positioned corresponding row in result set     cursor cursor = (cursor) listview.getitematposition(position);  // state's capital row in database.     }    });    }    }         

the variable db local variable within oncreate method. use instance variable instead:

class /* ... */ {     private sqlitedatabase db;     /* ... */     @override     public void oncreate(bundle savedinstancestate) {         /* ... */         db = repo.getwritabledatabase();         /* ... */     }     /* ... */ }