BluetoothGattCallback.java

// code to add to slides, not a complete implementation

public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {

  if (newState == BluetoothGatt.STATE_CONNECTED) {
    this.gatt = gatt;
    gatt.discoverServices();
  }
}

public void onServicesDiscovered(BluetoothGatt gatt, int status) {
  BluetoothGattService service = gatt.getService(SERVICE_UUID);
  // TODO handler errors if null
  switchCharacteristic = service.getCharacteristic(SWITCH_UUID);
  brightnessCharacteristic = service.getCharacteristic(DIMMER_UUID);
}