title: How to save BluetoothGatt Instance on Android?
body: <p>I'm currently developing an Android app which have interactions with BLE device. </p>
  
  <p>I have successfully connect a BLE device with the GATT server using the connectGatt() method. Now I want to use the BluetoothGatt instance returned in another activity. Is there anyway that I can save this BluetoothGatt Instance and use it in another activity without reconnecting to the BLE device which is already connected?</p>