Android 10 Bluetooth LE Scan Issues

Question

I am trying to get a simple Bluetooth LE Scanning app working under Android 10

The Scan starts but does not discover the devices.

There is a lot of traffic about correct permissions needed for Android 10 and I think I have them correct, Currently, I am requiring and asking the user for:

BLUETOOTH BLUETOOTH_ADMIN ACCESS_FINE_LOCATION FOREGROUND_SERVICE ACCESS_BACKGROUND_LOCATION

The app is simple, just a single form, a start scan button, a stop scan button and a textview to show the results.

Can someone point out what i have missed?

Many thanks

public class MainActivity extends AppCompatActivity {

BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;

Button startScanningButton;
Button stopScanningButton;
TextView peripheralTextView;


private static final int REQUEST_ENABLE_BT = 1;
private static final int PERMISSION_REQUEST_FINE_LOCATION = 1;
private static final int PERMISSION_REQUEST_BACKGROUND_LOCATION = 2;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    BottomNavigationView navView = findViewById(R.id.nav_view);
    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    AppBarConfiguration appBarConfiguration = new AppBarConfiguration.Builder(
            R.id.navigation_home, R.id.navigation_dashboard, R.id.navigation_notifications)
            .build();
    NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
    NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);
    NavigationUI.setupWithNavController(navView, navController);


    peripheralTextView = (TextView) findViewById(R.id.PeripheralTextView);
    peripheralTextView.setMovementMethod(new ScrollingMovementMethod());

    startScanningButton = (Button) findViewById(R.id.StartScanButton);
    startScanningButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            startScanning();
        }
    });

    stopScanningButton = (Button) findViewById(R.id.StopScanButton);
    stopScanningButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            stopScanning();
        }
    });
    stopScanningButton.setVisibility(View.INVISIBLE);


    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (this.checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            if (this.checkSelfPermission(Manifest.permission.ACCESS_BACKGROUND_LOCATION)
                    != PackageManager.PERMISSION_GRANTED) {
                if (this.shouldShowRequestPermissionRationale(Manifest.permission.ACCESS_BACKGROUND_LOCATION)) {
                    final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.setTitle("This app needs background location access");
                    builder.setMessage("Please grant location access so this app can detect beacons in the background.");
                    builder.setPositiveButton(android.R.string.ok, null);
                    builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                        @TargetApi(23)
                        @Override
                        public void onDismiss(DialogInterface dialog) {
                            requestPermissions(new String[]{Manifest.permission.ACCESS_BACKGROUND_LOCATION},
                                    PERMISSION_REQUEST_BACKGROUND_LOCATION);
                        }

                    });
                    builder.show();
                }
                else {
                    final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                    builder.setTitle("Functionality limited");
                    builder.setMessage("Since background location access has not been granted, this app will not be able to discover beacons in the background.  Please go to Settings -> Applications -> Permissions and grant background location access to this app.");
                    builder.setPositiveButton(android.R.string.ok, null);
                    builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                        @Override
                        public void onDismiss(DialogInterface dialog) {
                        }

                    });
                    builder.show();
                }

            }
        } else {
            if (!this.shouldShowRequestPermissionRationale(Manifest.permission.ACCESS_FINE_LOCATION)) {
                requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION,
                                Manifest.permission.ACCESS_BACKGROUND_LOCATION},
                        PERMISSION_REQUEST_FINE_LOCATION);
            }
            else {
                final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setTitle("Functionality limited");
                builder.setMessage("Since location access has not been granted, this app will not be able to discover beacons.  Please go to Settings -> Applications -> Permissions and grant location access to this app.");
                builder.setPositiveButton(android.R.string.ok, null);
                builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                    @Override
                    public void onDismiss(DialogInterface dialog) {
                    }

                });
                builder.show();
            }

        }
    }


    final BluetoothManager btManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);

    btAdapter = btManager.getAdapter();

    if (btAdapter == null || !btAdapter.isEnabled()) {
        Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableIntent,REQUEST_ENABLE_BT);
    }


    btScanner = btAdapter.getBluetoothLeScanner();

}


// Device scan callback.
private ScanCallback leScanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        peripheralTextView.append("Device Name: " + result.getDevice().getName() + " rssi: " + result.getRssi() + "\n");
    }
};

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case PERMISSION_REQUEST_FINE_LOCATION: {
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                System.out.println("fine location permission granted");
            } else {
                final AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setTitle("Functionality limited");
                builder.setMessage("Since location access has not been granted, this app will not be able to discover devices when in the background.");
                builder.setPositiveButton(android.R.string.ok, null);
                builder.setOnDismissListener(new DialogInterface.OnDismissListener() {

                    @Override
                    public void onDismiss(DialogInterface dialog) {
                    }

                });
                builder.show();
            }
            return;
        }
    }
}

public void startScanning() {
    peripheralTextView.setText("");
    peripheralTextView.append("Start Scanning");
    startScanningButton.setVisibility(View.INVISIBLE);
    stopScanningButton.setVisibility(View.VISIBLE);
    AsyncTask.execute(new Runnable() {
        @Override
        public void run() {
            btScanner.startScan(leScanCallback);
        }
    });
}

public void stopScanning() {
    peripheralTextView.append("Stopped Scanning");
    startScanningButton.setVisibility(View.VISIBLE);
    stopScanningButton.setVisibility(View.INVISIBLE);
    AsyncTask.execute(new Runnable() {
        @Override
        public void run() {
            btScanner.stopScan(leScanCallback);
        }
    });
}

}

Answer 1

I know I'm a bit to late but I hope this help someone.

Those permissions are correct. You are not enabling location services and that's your issue.

Take a look at this. As you can see there is a lot of discussion about the why Google make the things that way. At the very end of the issue, there is a Youtube video link (see it here) where Chet explained that even Google not know what is like that, so they added a new permission in A12.

Also

Android 10 permissions:
On Android 10, you generally must have obtained ACCESS_BACKGROUND_LOCATION for beacon detection to work when your app is not visible. However, it is possible to scan with only foreground location permission granted and a foreground service if you add android:foregroundServiceType="location" to your foreground service declaration in the manifest. See here for details.

So, enabling location services will be enough to get your results with

bluetoothMangaer.adapter.startScan(scanCallback)

In the case you dont want the user to enable his location, you can do a

bluetoothMangaer.adapter.startDiscovery()

Answer 2

It seems Bluetooth scanning is disable. Please find below screenshot. Only location enable will not work along with location you need to enable Bluetooth scanning.

Answer 3

It seems it was something to do with the adapter itself causing the problem, looking at logcat I was getting a status=133 on the startscanning call, resetting the physical adapter cleared the issue and scan results began appearing