title: how can I reconnect my application at every opening to the same bluetooth low energy device?
body: <p>I'm developing an Android app. At the start this app show to the user a list of bluetooth devices and when he chooses one of they  opens an other activity.</p>
  
  <p>My goal is : after some day  when the user will reopen the app the app will have to remember the ble device and it have to try to reconnect to it.</p>
  
  <p>For now I have obtained my goal in this way :</p>
  
  <ul>
  <li>I memorize in preference the mac address of the chosen device </li>
  <li>When the user reopen the app the app do a hidden scan and try to reconnect to a device with a same MAC address.</li>
  <li>for retrieve the mac address I use the function getAddress() (when I try to connect to the android peripheral this function gives me
  some problem, because the  the device changes his MAC address at each
  starts :/)</li>
  </ul>
  
  <p>There is a best way to obtain the same thing ? </p>
  
  <p>Off topic : The function  onScanResult in the ScanResult some time return to me null device, is it normal ?
  I have uses startLeScan(UUID[] serviceUuids, BluetoothAdapter.LeScanCallback callback) and after lollipop I use the new version of the startLeScan with Scanfilter. Can it be the problem ?</p>