detect bluetooth Le devices in Android

Question

I'm a beginner in android app development. I've tried reading the documentation but am getting nowhere (functions in Android's tutorial such as StartLeScan() have been deprecated, etc...)

Is there a simple function that returns a list of bluetooth devices ?

something like getDevices() -> (list of devices) ?

Thank you

Answer 1

basically it depends on which android version you are targeting. since the api has changed a bit in lollipop (21).

in your activity, get the bluetooth adapter

BluetoothManager bm = (BluetoothManager)getSystemService(Context.BLUETOOTH_SERVICE)
BluetoothAdapter mBluetoothAdapter = bm.getAdapter();

// Ensures Bluetooth is available on the device and it is enabled. If not, 
// displays a dialog requesting user permission to enable Bluetooth. 
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) { 
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

then you should check which android version you are targeting

int apiVersion = android.os.Build.VERSION.SDK_INT;
if (apiVersion > android.os.Build.VERSION_CODES.KITKAT){
 BluetoothLeScanner scanner = mBluetoothAdapter.getBluetoothLeScanner();
 // scan for devices
 scanner.startScan(new ScanCallback() {
        @Override
        public void onScanResult(int callbackType, ScanResult result) {
            // get the discovered device as you wish
            // this will trigger each time a new device is found

            BluetoothDevice device = result.getDevice();
        }
    });
} else {
    // targetting kitkat or bellow
    mBluetoothAdapter.startLeScan(new BluetoothAdapter.LeScanCallback() {
        @Override
        public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {
            // get the discovered device as you wish

        }
    });

// rest of your code that will run **before** callback is triggered since it's asynchronous

dont forget to add permissions in your manifest

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