Simple Android BLE Scanner

Question

I'm trying to create a simple android application with which I can scan Bluetooth Low Energy (BLE) devices and print names as Log. The main activity is very basic, I don't need checks, I suppose that is all right. The scan starts, but I have not results.

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.s1080994.tid.findble">


    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />


    <uses-feature
        android:name="android.hardware.bluetooth_le"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private BluetoothAdapter mBluetoothAdapter  = null;
    private BluetoothLeScanner mBluetoothLeScanner = null;

    public static final int REQUEST_BT_PERMISSIONS = 0;
    public static final int REQUEST_BT_ENABLE = 1;

    private boolean mScanning = false;
    private Handler mHandler = null;

    private Button btnScan = null;

    private ScanCallback mLeScanCallback =
            new ScanCallback() {

                @Override
                public void onScanResult(int callbackType, final ScanResult result) {
                    //super.onScanResult(callbackType, result);
                    Log.i("BLE", result.getDevice().getName());

                }

                @Override
                public void onScanFailed(int errorCode) {
                    super.onScanFailed(errorCode);
                    Log.i("BLE", "error");
                }
            };



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnScan = (Button) findViewById(R.id.btnScan);

        this.mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        this.mBluetoothLeScanner = mBluetoothAdapter.getBluetoothLeScanner();
        this.mHandler = new Handler();

        checkBtPermissions();
        enableBt();
    }

    public void onBtnScan(View v){
        if (mScanning){
            mScanning = false;
            scanLeDevice(false);
            btnScan.setText("STOP");
        } else {
            mScanning = true;
            scanLeDevice(true);
            btnScan.setText("SCAN");
        }
    }

    public void checkBtPermissions() {
        this.requestPermissions(
                new String[]{
                        Manifest.permission.BLUETOOTH, Manifest.permission.BLUETOOTH_ADMIN
                },
                REQUEST_BT_PERMISSIONS);
    }

    public void enableBt(){
        if (mBluetoothAdapter == null) {
            // Device does not support Bluetooth
        }
        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_BT_ENABLE);
        }
    }

    public void scanLeDevice(final boolean enable) {
        //ScanSettings mScanSettings = new ScanSettings.Builder().setScanMode(ScanSettings.SCAN_MODE_BALANCED).setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES).build();

        if (enable) {
            mScanning = true;
            Log.i("Scanning", "start");
            mBluetoothLeScanner.startScan(mLeScanCallback);
        } else {
            Log.i("Scanning", "stop");
            mScanning = false;
            mBluetoothLeScanner.stopScan(mLeScanCallback);
        }
    }
}

Answer 1

You need to enable location/gps settings in order to scan BLE devices nearby on android. Please enable location/gps and try to scan.