Bluetooth Low Energy device scanning Failed with an exception

Question

I am referring to developer docs to scan BLE devices -

http://developer.android.com/guide/topics/connectivity/bluetooth-le.html

In my activity class LookUpActivity, I called a method findBLE() on a button click-

//This will scan BLE devices
public void findBLE()
{
    Intent intent = new Intent(LookUpActivity.this, DeviceScanActivity.class);
    startActivity(intent);
}

But got the following exception -

Could not find class 'com.testapp.main.DeviceScanActivity$1', 
referenced from method com.testapp.main.DeviceScanActivity.<init>


com.testapp.main fatal error : com.testapp.main.DeviceScanActivity$1
java.lang.NoClassDefFoundError: com.testapp.main.DeviceScanActivity$1   
at com.testapp.main.DeviceScanActivity.<init>(DeviceScanActivity.java:179)

DeviceScanActivity.java ---

/**
 * Activity for scanning and displaying available Bluetooth LE devices.
 */
@SuppressLint("NewApi")
public class DeviceScanActivity extends ListActivity {
    private LeDeviceListAdapter mLeDeviceListAdapter;
    private BluetoothAdapter mBluetoothAdapter;
    private boolean mScanning;
    private Handler mHandler;

    private static final int REQUEST_ENABLE_BT = 1;
    // Stops scanning after 10 seconds.
    private static final long SCAN_PERIOD = 10000;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mHandler = new Handler();
    }

    @Override
    protected void onResume() {
        super.onResume();

        // Ensures Bluetooth is enabled on the device.  If Bluetooth is not currently enabled,
        // fire an intent to display a dialog asking the user to grant permission to enable it.
        if (!mBluetoothAdapter.isEnabled()) {
            if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            }
        }

        // Initializes list view adapter.
        mLeDeviceListAdapter = new LeDeviceListAdapter();
        setListAdapter(mLeDeviceListAdapter);
        scanLeDevice(true);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // User chose not to enable Bluetooth.
        if (requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_CANCELED) {
            finish();
            return;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    @Override
    protected void onPause() {
        super.onPause();
        scanLeDevice(false);
        mLeDeviceListAdapter.clear();
    }

    private void scanLeDevice(final boolean enable) {
        if (enable) {
            // Stops scanning after a pre-defined scan period.
            mHandler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    mScanning = false;
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                }
            }, SCAN_PERIOD);

            mScanning = true;
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mScanning = false;
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        }
    }

    // Adapter for holding devices found through scanning.
    private class LeDeviceListAdapter extends BaseAdapter {
        private ArrayList<BluetoothDevice> mLeDevices;
        private LayoutInflater mInflator;

        public LeDeviceListAdapter() {
            super();
            mLeDevices = new ArrayList<BluetoothDevice>();
            mInflator = DeviceScanActivity.this.getLayoutInflater();
        }

        public void addDevice(BluetoothDevice device) {
            if(!mLeDevices.contains(device)) {
                mLeDevices.add(device);
            }
        }

        public BluetoothDevice getDevice(int position) {
            return mLeDevices.get(position);
        }

        public void clear() {
            mLeDevices.clear();
        }

        @Override
        public int getCount() {
            return mLeDevices.size();
        }

        @Override
        public Object getItem(int i) {
            return mLeDevices.get(i);
        }

        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder viewHolder;
            // General ListView optimization code.
            if (view == null) {
                view = mInflator.inflate(R.layout.mapentries, null);
                viewHolder = new ViewHolder();
                viewHolder.deviceAddress = (TextView) view.findViewById(R.id.entriestitle);
                //viewHolder.deviceName = (TextView) view.findViewById(R.id.device_name);
                view.setTag(viewHolder);
            } else {
                viewHolder = (ViewHolder) view.getTag();
            }

            BluetoothDevice device = mLeDevices.get(i);
            final String deviceName = device.getName();
           /* if (deviceName != null && deviceName.length() > 0)
                viewHolder.deviceName.setText(deviceName);
            else
                viewHolder.deviceName.setText(R.string.unknown_device);*/

            viewHolder.deviceAddress.setText(device.getAddress());

            return view;
        }
    }

    // Device scan callback.
    private BluetoothAdapter.LeScanCallback mLeScanCallback =
            new BluetoothAdapter.LeScanCallback() { //This is line 179 causing error...

        @Override
        public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mLeDeviceListAdapter.addDevice(device);
                    mLeDeviceListAdapter.notifyDataSetChanged();
                }
            });
        }
    };

    static class ViewHolder {
        //TextView deviceName;
        TextView deviceAddress;
    }
}

UPDATE:

In order to be more specific, I downloaded the exact project code for BLE from ---

http://developer.android.com/samples/BluetoothLeGatt/project.html

And again got the same exception even using the code mentioned in the project.

This time the error console--

FATAL EXCEPTION: main
java.lang.NoClassDefFoundError:   
com.example.android.bluetoothlegatt
.DeviceScanActivity$1
at com.example.android.bluetoothlegatt.DeviceScanActivity.
<init>  (DeviceScanActivity.java:250)

Answer 1

You must perform the full check to see if the device supports Bluetooth Low Energy (BLE). The device could be running Android 4.3 or later but lacks the hardware necessary for BLE. The Nexus 7 (2012) is an example of such device. Here's the code:

  private boolean bleCheck() {
    boolean result = false;
    if (getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
      mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
      if (mBluetoothManager != null) {
        mBluetoothAdapter = mBluetoothManager.getAdapter();
        if (mBluetoothAdapter != null) {
          if (mBluetoothAdapter.isEnabled()) {
            result = true;
          }
        }
      }
    }
    return result;
  }