android - Error while Listing scanned Bluetooth Low Energy Device -

i developing android application scans , displays bluetooth low energy devices in listview. problem able display 1 item in listview if there many ble devices.i using arraylist , arrayadapter essential.below part of code, can tell me error , how can overcome it.

public class scanlist extends activity { public  listview scandevicelist; private  bluetoothadapter mbluetoothadapter; private  handler mhandler; private  arrayadapter<bluetoothdevice> adapter1; context context; activity activity; public  arraylist<bluetoothdevice> devices; public string mdeviceaddress,mdevicename; private static final int request_enable_bt = 1; // stops scanning after 10 seconds. private static final long scan_period = 10000;    @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.scanned_device);     scandevicelist = (listview) findviewbyid(r.id.scandevicelist);     mhandler = new handler();     final bluetoothmanager bluetoothmanager = (bluetoothmanager) getsystemservice(context.bluetooth_service);     mbluetoothadapter = bluetoothmanager.getadapter();  } @override protected void onresume() {     super.onresume();      if (!mbluetoothadapter.isenabled()) {         intent enablebtintent = new intent(bluetoothadapter.action_request_enable);         startactivityforresult(enablebtintent, request_enable_bt);     }       scanledevice(true); }  public  void scanledevice(final boolean enable) {     if (enable) {         // stops scanning after pre-defined scan period.         mhandler.postdelayed(new runnable() {             @override             public void run() {                 mscanning = false;                 mbluetoothadapter.stoplescan(mlescancallback);                 invalidateoptionsmenu();             }         }, scan_period);         mscanning = true;         mbluetoothadapter.startlescan(mlescancallback);     } else {         mscanning = false;         mbluetoothadapter.stoplescan(mlescancallback);     }     invalidateoptionsmenu(); }  public  bluetoothadapter.lescancallback mlescancallback =         new bluetoothadapter.lescancallback() {              @override             public void onlescan(final bluetoothdevice device, int rssi, byte[] scanrecord) {                 runonuithread(new runnable() {                     @override                     public void run() {                         devices = new arraylist<bluetoothdevice>();                         devices.add(device);                         adapter1 = new arrayadapter<bluetoothdevice>(scandevicelist.getcontext(), android.r.layout.simple_list_item_1,devices);                         scandevicelist.setadapter(adapter1);                       }                  });              }           }; } 

each time scan , onlescan return 1 item (although many becons advertising)

devices = new arraylist<bluetoothdevice>();  public  bluetoothadapter.lescancallback mlescancallback =         new bluetoothadapter.lescancallback() {              @override             public void onlescan(final bluetoothdevice device, int rssi, byte[] scanrecord) {                 runonuithread(new runnable() {                     @override                     public void run() {                         devices.add(device);                     }                 });