Develop Reference

Running BLE ScanCallback in the background

I want to be able to scan for BLE tags in the background.
I have read about using Services to do this. However, when the service is executed and then I run another application on my phone, the BLE scan callback stops executing but the service still runs as normal.
I know the BLE callback stops because the log cat stops producing the log data until I open the application again.
Below is my MainActiivity:
public class MainActivity extends AppCompatActivity {
BluetoothManager btManager;
BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;
Button startScanningButton;
Button stopScanningButton;
TextView peripheralTextView;
private NotificationManagerCompat notificationManager;
private final static int REQUEST_ENABLE_BT = 1;
private static final int PERMISSION_REQUEST_COARSE_LOCATION = 1;
private static final String TAG = "ExampleJobService";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate MAIN");
notificationManager = NotificationManagerCompat.from(this);
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) {
Log.d(TAG, "Start button");
startService(new Intent(MainActivity.this, ExampleService.class));
}
});
stopScanningButton = (Button) findViewById(R.id.StopScanButton);
stopScanningButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Log.d(TAG, "Stop 1");
Intent serviceIntent = new Intent(MainActivity.this, ExampleService.class);
stopScanning();
stopService(serviceIntent);
Log.d(TAG, "Stop 2");
}
});
btManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);
btAdapter = btManager.getAdapter();
btScanner = btAdapter.getBluetoothLeScanner();
if (btAdapter != null && !btAdapter.isEnabled()) {
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent,REQUEST_ENABLE_BT);
}
// Make sure we have access coarse location enabled, if not, prompt the user to enable it
if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("This app needs location access");
builder.setMessage("Please grant location access so this app can detect peripherals.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);
}
});
builder.show();
}
}
#Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_COARSE_LOCATION: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
System.out.println("coarse 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 beacons 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("");
AsyncTask.execute(new Runnable() {
#Override
public void run() {
btScanner.startScan(leScanCallback);
}
});
}
public void stopScanning() {
System.out.println("stopping scanning");
peripheralTextView.append("Stopped Scanning");
AsyncTask.execute(new Runnable() {
#Override
public void run() {
btScanner.stopScan(leScanCallback);
}
});
}
}
Below is the ExampleService:
public class ExampleService extends Service {
BluetoothManager btManager;
BluetoothAdapter btAdapter;
BluetoothLeScanner btScanner;
TextView peripheralTextView;
private NotificationManagerCompat notificationManager;
private static final String TAG = "ExampleJobService";
#Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate");
}
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand");
btManager = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE);
btAdapter = btManager.getAdapter();
btScanner = btAdapter.getBluetoothLeScanner();
//do heavy work on a background thread
AsyncTask.execute(new Runnable() {
#Override
public void run() {
btScanner.startScan(leScanCallback);
}
});
return START_REDELIVER_INTENT;
}
private ScanCallback leScanCallback = new ScanCallback() {
#RequiresApi(api = Build.VERSION_CODES.O)
#Override
public void onScanResult(int callbackType, ScanResult result) {
Log.d(TAG, "BLE executed");
if(result.getDevice().getAddress().equals("EE:7E:DE:9B:65:46") && result.getRssi() > -80){
Log.d(TAG, "Tag found");
}
}
};
#Override
public void onDestroy() {
Log.d(TAG, "Destroy");
super.onDestroy();
}
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
}
EDIT 1:
String[] peripheralAddresses = new String[]{"EE:7E:DE:9B:65:46"};
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand");
Intent notificationIntent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this,
0, notificationIntent, 0);
Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
.setContentTitle("Example Service")
.setContentText("input")
.setSmallIcon(R.drawable.ic_one)
.setContentIntent(pendingIntent)
.build();
startForeground(1, notification);
ScanSettings settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_POWER)
.build();
// Build filters list
List<ScanFilter> filters = null;
if (peripheralAddresses != null) {
filters = new ArrayList<>();
for (String address : peripheralAddresses) {
ScanFilter filter = new ScanFilter.Builder()
.setDeviceAddress(address)
.build();
filters.add(filter);
}
}
btScanner.startScan(filters, settings, leScanCallback);
return START_STICKY;
}

First, I recommend you to add Scan filters, because Android stops scan after some time if you scan without them.
Second, Your service will not live for a long time, because Android will kill it, if your device's Android versions is more or equal Android Oreo (Android 8).
So I recommend you to read this article for finding better solution.
Hope, this will help you!

on App resume beaconmanager fails to detect beacon using Android Beacon Library

First time I run the app beacon monitoring and ranging is working fine. But the second time I lanuch the app i.e after calling onResume it is only showing following and no more calls to didRangeBeaconsInRegion : I am guessing it is because of beaconManager instance is not properly destroyed or something in calls to onDestroy. However according to the library example I tried unbinding in onPause() with no success. Any idea ?
I/MonitoringActivity: I have just switched from seeing/not seeing beacons: 0
2020-07-15 18:41:40.776 9657-9657/com.something.beacon I/MonitoringActivity: I have just switched from seeing/not seeing beacons: 0
2020-07-15 18:41:40.824 9657-9657/com.something.beacon I/MonitoringActivity: I have just switched from seeing/not seeing beacons: 1
public class MainActivity extends AppCompatActivity implements BeaconConsumer {
private static final int PERMISSION_REQUEST_FINE_LOCATION = 1;
private static final int PERMISSION_REQUEST_BACKGROUND_LOCATION = 2;
ListView beaconList;
protected static final String TAG = "MonitoringActivity";
private BeaconManager beaconManager;
private FirebaseDatabase database;
private DatabaseReference beaconDBRef;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Firebase database setup
database = FirebaseDatabase.getInstance();
beaconDBRef = database.getReference().child("messages");
beaconList = (ListView) findViewById(R.id.beacon_list);
Log.d(TAG, "onCreate: is called");
beaconManager = BeaconManager.getInstanceForApplication(this);
beaconManager.getBeaconParsers().add(new BeaconParser().
setBeaconLayout("m:2-3=beac,i:4-19,i:20-21,i:22-23,p:24-24,d:25-25"));
// Detect the main identifier (UID) frame:
beaconManager.getBeaconParsers().add(new BeaconParser().
setBeaconLayout(BeaconParser.EDDYSTONE_UID_LAYOUT));
// Detect the telemetry (TLM) frame:
beaconManager.getBeaconParsers().add(new BeaconParser().
setBeaconLayout(BeaconParser.EDDYSTONE_TLM_LAYOUT));
// Detect the URL frame:
beaconManager.getBeaconParsers().add(new BeaconParser().
setBeaconLayout(BeaconParser.EDDYSTONE_URL_LAYOUT));
beaconManager.bind(this);
verifyBluetooth();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (this.checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
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();
}
}
}
}
#Override
protected void onResume() {
super.onResume();
}
#Override
protected void onDestroy() {
super.onDestroy();
beaconManager.unbind(this);
}
long tempTime = Integer.MIN_VALUE;
long callInterval = 10000;
#Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSION_REQUEST_FINE_LOCATION: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "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 nearby devices.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
}
});
builder.show();
}
return;
}
case PERMISSION_REQUEST_BACKGROUND_LOCATION: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "background location permission granted");
} 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 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;
}
}
}
private void verifyBluetooth() {
try {
if (!BeaconManager.getInstanceForApplication(this).checkAvailability()) {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Bluetooth not enabled");
builder.setMessage("Please enable bluetooth in settings and restart this application.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
//finish();
//System.exit(0);
}
});
builder.show();
}
}
catch (RuntimeException e) {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Bluetooth LE not available");
builder.setMessage("Sorry, this device does not support Bluetooth LE.");
builder.setPositiveButton(android.R.string.ok, null);
builder.setOnDismissListener(new DialogInterface.OnDismissListener() {
#Override
public void onDismiss(DialogInterface dialog) {
//finish();
//System.exit(0);
}
});
builder.show();
}
}
#Override
public void onBeaconServiceConnect() {
// Set the two identifiers below to null to detect any beacon regardless of identifiers
Identifier myBeaconNamespaceId = Identifier.parse("0x2F234454F4911BA9FFA6");
final Identifier myBeaconInstanceId = Identifier.parse("0x000000000001");
beaconManager.removeAllMonitorNotifiers();
beaconManager.removeAllRangeNotifiers();
beaconManager.addMonitorNotifier(new MonitorNotifier() {
#Override
public void didEnterRegion(Region region) {
Log.i(TAG, "I just saw an beacon for the first time!");
try {
Log.d(TAG, "didEnterRegion");
beaconManager.startRangingBeaconsInRegion(region);
} catch (RemoteException e) {
e.printStackTrace();
}
}
#Override
public void didExitRegion(Region region) {
Log.i(TAG, "I no longer see an beacon");
try {
Log.d(TAG, "didExitRegion");
beaconManager.stopRangingBeaconsInRegion(region);
} catch (RemoteException e) {
e.printStackTrace();
}
}
#Override
public void didDetermineStateForRegion(int state, Region region) {
Log.i(TAG, "I have just switched from seeing/not seeing beacons: "+state);
}
});
beaconManager.addRangeNotifier(new RangeNotifier() {
#Override
public void didRangeBeaconsInRegion(Collection<Beacon> beacons, Region region) {
for(Beacon oneBeacon : beacons) {
String beaconInfo = "Namespace id: " + oneBeacon.getId1() + "\nInstance Id: " + oneBeacon.getId2();
Log.d(TAG, beaconInfo);
Toast.makeText(MainActivity.this, beaconInfo, Toast.LENGTH_SHORT).show();
//Write to database every 10 seconds
long currentTime = System.currentTimeMillis();
if(currentTime > tempTime + callInterval){
BeaconModel beaconModel = new BeaconModel();
beaconModel.setBeaconName(oneBeacon.getId2().toString());
beaconModel.setDistance(oneBeacon.getDistance());
beaconModel.setMessage("this is a nice message");
beaconDBRef.child(beaconModel.getBeaconName()).setValue(beaconModel);
//beaconDBRef.push().setValue("beacon detected! - " + oneBeacon.getId2());
tempTime = currentTime;
}
}
}
});
try {
Identifier myBeaconNamespaceId1 = Identifier.parse("0xedd1ebeac04e5defa017");
Identifier myBeaconInstanceId1 = Identifier.parse("0x0e32fea91b13");
Identifier myBeaconInstanceId2 = Identifier.parse("0xa9937b420872");
beaconManager.startMonitoringBeaconsInRegion(new Region("myMonitoringUniqueId", myBeaconNamespaceId1, myBeaconInstanceId1, null));
beaconManager.startMonitoringBeaconsInRegion(new Region("myMonitoringUniqueId2", myBeaconNamespaceId1, myBeaconInstanceId2, null));
beaconManager.startMonitoringBeaconsInRegion(new Region("myMonitoringUniqueId3", null, null, null));
} catch (RemoteException e) {
Log.d(TAG, e.getMessage());
}
}
}

Problem in scanning Bluetooth LE devices (no callback)

I am trying to develop an Android app capable to connect to a BLE device. But i have a problem to find ble devices. The scanLeDevice methods run but I have no callback. You can find my code below: I use Log.i() to display ble devices.
With another app (downloaded from the store) I can find my ble device and others bluetooth around. So It's not my phone's problem.
Thanks for help!
public class MainActivity extends AppCompatActivity {
private BluetoothAdapter bluetoothAdapter;
private final int REQUEST_ENABLE_BT = 1;
private boolean mScanning;
// Stops scanning after 10 seconds.
private static final long SCAN_PERIOD = 10000;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i("MainActivity", "Begin");
// Initializes Bluetooth adapter.
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();
// Ensures Bluetooth is available on the device and it is enabled. If not,
// displays a dialog requesting user permission to enable Bluetooth.
if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
Log.i("MainActivity", "End for permissions");
if(Build.VERSION.SDK_INT < 21){
scanLeDevice(true);
}else{
scanDevice(true);
}
}
private Handler handler = new Handler();
private void scanLeDevice(final boolean enable) {
if (enable) {
// Stops scanning after a pre-defined scan period.
handler.postDelayed(new Runnable() {
#Override
public void run() {
mScanning = false;
bluetoothAdapter.stopLeScan(leScanCallback);
}
}, SCAN_PERIOD);
mScanning = true;
bluetoothAdapter.startLeScan(leScanCallback);
Log.i("MainActivity", "scanning");
} else {
mScanning = false;
bluetoothAdapter.stopLeScan(leScanCallback);
}
}
// Device scan callback.
private BluetoothAdapter.LeScanCallback leScanCallback =
new BluetoothAdapter.LeScanCallback() {
#Override
public void onLeScan(final BluetoothDevice device, int rssi,
byte[] scanRecord) {
runOnUiThread(new Runnable() {
#Override
public void run() {
//Ici///////////////////////////////////////
Log.i("MainActivity", "Nam: "+device.getName()+" Adresse: "+device.getAddress());
if(device.getName() != null && device.getName().equals("RN4871-85D7"))
scanLeDevice(false);
}
});
}
};
///////////////////Scan for API 21
private ScanSettings settings;
private List<ScanFilter> filters;
private BluetoothLeScanner mLEScanner;
private void scanDevice(final boolean enable){
if (mLEScanner==null){
mLEScanner = bluetoothAdapter.getBluetoothLeScanner();
settings = new ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.build();
filters = new ArrayList<ScanFilter>();
}
if (enable) {
if (mScanning) return;
// Stops scanning after a pre-defined scan period.
handler.postDelayed(new Runnable() {
#Override
public void run() {
if (!mScanning) return;
try {
mScanning = false;
//Log.d("MainActivity","STOP SCAN AFTER DELAY");
mLEScanner.stopScan(mScanCallback);
Log.i("MainActivity", "stop scanning API 21");
} catch (Exception e){Log.e("MainActivity",e.getMessage());}
}
}, SCAN_PERIOD);
mScanning = true;
//Log.d("MainActivity","START SCAN FROM EXPLICIT CALL");
mLEScanner.startScan(filters, settings, mScanCallback);
Log.i("MainActivity", "scanning API 21");
} else if (mLEScanner!=null){
if (!mScanning) return;
mScanning = false;
try {
//Log.d("MainActivity","STOP SCAN FROM EXPLICIT CALL");
mLEScanner.stopScan(mScanCallback);
Log.i("MainActivity", "stop scanning API 21");
} catch (Exception e){Log.i("MainActivity",e.getMessage());}
}
}
//call back for API 21
//#TargetApi(21)
private ScanCallback mScanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
super.onScanResult(callbackType, result);
Log.i("MainActivity", "onScanResult API 21");
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
super.onBatchScanResults(results);
Log.i("MainActivity", "onBatchScanResults API 21");
}
#Override
public void onScanFailed(int errorCode) {
super.onScanFailed(errorCode);
Log.i("MainActivity", "onScanFailed API 21");
}
};
}
Thanks for your help``

I found what was the problem about the location.
In fact, if you work with a API >= 23, you have to authorize you app to access to the location (not only in the Manifest file, but in you code it self).
So if you have the same problem:
First, manualy, go to your phon's setting and autorize your app to access to location: to be sure that was the problem.
Then add the code below so that, The application ask the user to authorize the application to access the location
/////////////////////////Location/////
#TargetApi(Build.VERSION_CODES.M)
private void loadPermissions(String perm,int requestCode) {
if (ContextCompat.checkSelfPermission(this, perm) != PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, perm)) {
ActivityCompat.requestPermissions(this, new String[]{perm},requestCode);
}
} else if (checkLocationEnabled())
initScanner();
}
private boolean checkLocationEnabled(){
LocationManager lm = (LocationManager)this.getSystemService(Context.LOCATION_SERVICE);
boolean gps_enabled = false;
boolean network_enabled = false;
try {
gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
} catch(Exception ex) {}
try {
network_enabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
} catch(Exception ex) {}
if(!gps_enabled && !network_enabled) {
// notify user
AlertDialog.Builder dialog = new AlertDialog.Builder(this);
dialog.setMessage("GPS desabled");
dialog.setPositiveButton("Open GPS settings", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface paramDialogInterface, int paramInt) {
// TODO Auto-generated method stub
Intent myIntent = new Intent( Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(myIntent);
//get gps
}
});
dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface paramDialogInterface, int paramInt) {
// TODO Auto-generated method stub
}
});
dialog.show();
return false;
} else return true;
}
#Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
switch (requestCode) {
case REQUEST_FINE_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// granted
if (checkLocationEnabled())
initScanner();
}
else{
// no granted
}
return;
}
}
}

I had this problem too because I was using ACCESS_COARSE_LOCATION on the permission.
When I changed to ACCESS_FINE_LOCATION, it finally works for me!

Bluetooth BLE ScanCallback stopped working

I am working on BLE devices android application. i am trying to get available bluetooth devices using scanCallBack. It was working fine some days ago but suddenly it stopped. onScanResults or onScanFailed nothing are NOT executing. I have given the ACCESS_COARSE_LOCATION, BLUETOOTH_ADMIN, BLUETOOTH and ACCESS_FINE_LOCATION in manifest and request permissions at run time also.Bluetooth is on and location is also on. Please help.
Measurement.java
public class MeasurementScreen extends AppCompatActivity {
private BluetoothAdapter bluetoothAdapter;
static int REQUEST_ENABLE_BT = 1001;
private Boolean spinnerStatus= false;
private Handler handler = new Handler(Looper.getMainLooper());
final BluetoothAdapter mBluetoothAdapter =
BluetoothAdapter.getDefaultAdapter();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.device_reading_screen);
Objects.requireNonNull(getSupportActionBar()).hide();
if (Build.VERSION.SDK_INT >= 23) {
int permissionCheck = ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_COARSE_LOCATION);
if (permissionCheck == -1 ) {
ActivityCompat.requestPermissions(this,
new String[]{
Manifest.permission.ACCESS_COARSE_LOCATION
}, 0);
}
}
final Button tryAgain = findViewById(R.id.tryagain);
next = findViewById(R.id.next);
back = findViewById(R.id.back);
progressDialog = new ProgressDialog(this);
bluetoothscan();
}
void bluetoothscan(){
spinner();
scanBLEDevices(true);
}
private void scanBLEDevices(final boolean enable){
final BluetoothLeScanner bluetoothLeScanner = mBluetoothAdapter.getBluetoothLeScanner();
final BLEScanCallback scanCallback = new BLEScanCallback();
if (enable){
// Stops scanning after a pre-defined scan period.
handler.postDelayed(new Runnable() {
#Override
public void run() {
mScanning = false;
bluetoothLeScanner.stopScan(scanCallback);
}
}, 10000);
mScanning = true;
bluetoothLeScanner.startScan(scanCallback);
}else{
mScanning = false;
bluetoothLeScanner.stopScan(scanCallback);
}
}
public class BLEScanCallback extends ScanCallback{
#Override
public void onScanResult(int callbackType, ScanResult result) {
super.onScanResult(callbackType, result);
Log.e("Scan Success", "Scan Success");
}
#Override
public void onBatchScanResults(List<ScanResult> results) {
super.onBatchScanResults(results);
Log.e("Scan Success", "Scan Success Batch");
}
#Override
public void onScanFailed(int errorCode) {
super.onScanFailed(errorCode);
Log.e("Scan Failed", "Error Code: " + errorCode);
}
}
}
This is the log output:-
D/BluetoothAdapter: STATE_ON
D/BluetoothLeScanner: onClientRegistered() - status=0 clientIf=6
mClientIf=0

Bluetooth LE devices not detected

My app needs to connect to a Bluetooth Low Energy device, and obviously the first step is to detect it. I have written the code bellow to do just that. When I run the app I have another BLE device (Xperia M2) beside my Dev phone (Huawei P8 Lite) with Bluetooth ON and discoverable, however, nothing get printed on the logcat. Is the device truly not being discovered or is the callback function not being called/malfunctioning. What can I do to identify which one of this situations is happening?
The scanBluetoothMethod is called elsewhere in the code.
private BluetoothManager bluetoothManager;
private BluetoothAdapter bluetoothAdapter;
private static final long SCAN_PERIOD = 10000;
private BluetoothLeScanner scanner;
private Handler scanHandler = new Handler();
private List<ScanFilter> scanFilters = new ArrayList<ScanFilter>();
private ScanSettings scanSettings;
private boolean scanRunning=false;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_pandlet);
...
bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();
}
private void scanBluetoothLE() {
if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
return;
}
progressDialog = new ProgressDialog(this);
progressDialog.setMessage(getString(R.string.addpandlet_searchingforbledevices));
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progressDialog.setCancelable(false);
progressDialog.setCanceledOnTouchOutside(false);
progressDialog.setIndeterminate(true);
progressDialog.setButton(DialogInterface.BUTTON_NEUTRAL, getString(R.string.addpandlet_cancelsearch), new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
scanner.stopScan(scanCallback);
scanHandler.removeCallbacks(scanRunnable);
scanRunning = false;
return;
}
});
ScanSettings.Builder scanSettingsBuilder = new ScanSettings.Builder();
//scanSettingsBuilder.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES);
scanSettingsBuilder.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY);
scanSettings = scanSettingsBuilder.build();
scanHandler.post(scanRunnable);
}
private Runnable scanRunnable = new Runnable() {
#Override
public void run() {
scanner = BluetoothAdapter.getDefaultAdapter().getBluetoothLeScanner();
if (scanRunning) {
scanner.stopScan(scanCallback);
progressDialog.hide();
scanRunning = false;
} else {
scanRunning = true;
progressDialog.show();
scanHandler.postDelayed(this, SCAN_PERIOD);
scanner.startScan(scanFilters, scanSettings, scanCallback);
}
}
};
private ScanCallback scanCallback = new ScanCallback() {
#Override
public void onScanResult(int callbackType, ScanResult result) {
System.out.println(result.getRssi() + " " + result.getDevice().getName() );
super.onScanResult(callbackType, result);
}
#Override
public void onScanFailed(int errorCode) {
System.out.println("Error code " + errorCode );
super.onScanFailed(errorCode);
}
};
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
if( requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_OK )
scanBluetoothLE();
}

From the code - BluetoothAdapter.getDefaultAdapter().getBluetoothLeScanner(); it seems you are trying to scan bluetooth low energy devices..The device you are using I guess supports only classic bluetooth.
Try using devices which advertise bluetooth low energy services.You can build a app which advertise ble services on a device which supports bluetooth low energy.
Just to be sure, you can go to Settings->bluetooth and scan to check whether the device is being discovered by the default device bluetooth module.
Also you can check whether the device is detected by some other standard apps on playstore-https://play.google.com/store/apps/details?id=no.nordicsemi.android.mcp&hl=en