I write an Android App that should receive data from a Bluetooth low energy device. As a first step I try to scan for devices. Because the scan did not work I reduced my code to a minimum. When I click the checkPermissionBtn Log shows:
BLE_TESTApp: BLUETOOTH grated.
BLE_TESTApp: BLUETOOTH_ADMIN grated.
BLE_TESTApp: ACCESS_COARSE_LOCATION grated.
So I assume all permissions are o.k..
When I click searchBtn Log shows: BLE_TESTApp: Start scan... after 35 sec. BLE_TESTApp: Stop scan.
But leScanCallback is obviously not called. There is no Device found in the Log.
There is definitely at least one Bluetooth LE device available. I checked it with an Bluetooth LE Terminal App from the Appstore.
Wy does scan not found a device?
Here is my code:
public class MainActivity extends AppCompatActivity {
private static final String TAG = "BLE_TESTApp";
private Button searchBtn, checkPermissionBtn;
final int REQ_CODE_BLUETOOTH_PERMISSION = 42;
final int REQ_CODE_BLUETOOTH_ADMIN_PERMISSION = 43;
final int REQ_CODE_COARSE_PERMISSION = 44;
private BluetoothManager bluetoothManager;
private BluetoothAdapter bluetoothAdapter;
private BluetoothLeScanner bluetoothLeScannerLeScanner;
private final static int REQUEST_ENABLE_BT = 1;
private Handler handler = new Handler();
private static final long INTERVAL = 35000;
private ScanCallback leScanCallback = new ScanCallback() {
@Override
public void onScanResult(int callbackType, ScanResult result) {
Log.d(TAG, "Device found");
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
searchBtn = findViewById(R.id.searchBtn);
checkPermissionBtn = findViewById(R.id.cpBtn);
checkPermissionBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH) == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "BLUETOOTH grated.");
}else{
Log.d(TAG, "BLUETOOTH NOT grated!");
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH}, REQ_CODE_BLUETOOTH_PERMISSION);
}
if(ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH_ADMIN) == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "BLUETOOTH_ADMIN grated.");
}else{
Log.d(TAG, "BLUETOOTH_ADMIN NOT grated!");
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH_ADMIN}, REQ_CODE_BLUETOOTH_ADMIN_PERMISSION);
}
if(ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "ACCESS_COARSE_LOCATION grated.");
}else{
Log.d(TAG, "ACCESS_COARSE_LOCATION NOT grated!");
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, REQ_CODE_COARSE_PERMISSION);
}
}
});
bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();
bluetoothLeScannerLeScanner = bluetoothAdapter.getBluetoothLeScanner();
if (bluetoothAdapter != null && !bluetoothAdapter.isEnabled()) {
Log.d(TAG, "Bluetooth not enabled!");
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
}
searchBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.i(TAG, "Start scan...");
searchBtn.setEnabled(false);
AsyncTask.execute(new Runnable() {
@Override
public void run() {
bluetoothLeScannerLeScanner.startScan(leScanCallback);
}
});
handler.postDelayed(new Runnable() {
@Override
public void run() {
Log.i(TAG, "Stop scan.");
searchBtn.setEnabled(true);
AsyncTask.execute(new Runnable() {
@Override
public void run() {
bluetoothLeScannerLeScanner.stopScan(leScanCallback);
}
});
}
}, INTERVAL);
}
});
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if(requestCode == REQ_CODE_BLUETOOTH_PERMISSION && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "REQ_CODE_BLUETOOTH_PERMISSION granted.");
}
if(requestCode == REQ_CODE_BLUETOOTH_ADMIN_PERMISSION && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "REQ_CODE_BLUETOOTH_ADMIN_PERMISSION granted.");
}
if(requestCode == REQ_CODE_COARSE_PERMISSION && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
Log.d(TAG, "REQ_CODE_COARSE_PERMISSION granted.");
}
}
}
And the Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.bluetooth_le_test_03">
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.Bluetooth_Le_Test_03">
<activity android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
