android - Install apk file programmatically -

i have downloaded apk file localhost server using download manager api , displaying have downloaded file thing if click .apk file, unable install, give parsing package error. xml page

 <button         android:id="@+id/button1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:onclick="onclick"         android:text="start download" >     </button>      <button         android:id="@+id/button2"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:onclick="showdownload"         android:text="view downloads" >     </button> 

and here code

broadcastreceiver broad = new broadcastreceiver() {          @override         public void onreceive(context context, intent intent) {             // todo auto-generated method stub             string action = intent.getaction();              if (downloadmanager.action_download_complete.equals(action)) {                 long downloadid = intent.getlongextra(                         downloadmanager.extra_download_id, 0);                 query query = new query();                 query.setfilterbyid(enqueue);                 cursor c = dm.query(query);                 if (c.movetofirst()) {                     int columnindex = c                             .getcolumnindex(downloadmanager.column_status);                     if (downloadmanager.status_successful == c                             .getint(columnindex)) {                          // imageview view = (imageview)                         // findviewbyid(r.id.imageview1);                         final string uristring = c                                 .getstring(c                                         .getcolumnindex(downloadmanager.column_local_uri));                         // search.setimageuri(uri.parse(uristring));                      }                 }             }         }      };      registerreceiver(broad, new intentfilter(             downloadmanager.action_download_complete)); public void showdownload(view view) {     intent = new intent();     i.setaction(downloadmanager.action_view_downloads);     startactivity(i); } 

what procedure there install apk file there in downloadmanager?