Android bluetooth devices discovery

public class MainActivity extends AppCompatActivity {

    private BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    private TextView tvBoundedDevices;
    private TextView tvDiscoveredDevices;

    private IntentFilter intentFilter = new IntentFilter();
    private BroadcastReceiver broadcastReceiver;
    private ProgressDialog progressDialog;
    private ArrayList<BluetoothDevice> bluetoothDevicesFound = new ArrayList<>();
    private Set<BluetoothDevice> bluetoothDevicesBounded;

    @Override
    protected void onDestroy() {
        unregisterReceiver(broadcastReceiver);
        bluetoothAdapter.cancelDiscovery();
        super.onDestroy();
    }

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

        tvBoundedDevices = findViewById(R.id.tvBoundedDevices);
        tvDiscoveredDevices = findViewById(R.id.tvDiscoveredDevices);

        intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
        intentFilter.addAction(BluetoothDevice.ACTION_FOUND);
        intentFilter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        broadcastReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                switch (action){
                    case BluetoothAdapter.ACTION_DISCOVERY_STARTED:
                        progressDialog = ProgressDialog.show(MainActivity.this,"Attendere","Scan in corso");
                        break;
                    case BluetoothDevice.ACTION_FOUND:
                        bluetoothDevicesFound.add((BluetoothDevice) intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE));
                        break;
                    case BluetoothAdapter.ACTION_DISCOVERY_FINISHED:
                        if(progressDialog.isShowing())
                            progressDialog.dismiss();
                        break;
                    default:
                        Toast.makeText(context, "Action=" + action, Toast.LENGTH_LONG).show();
                }
            }
        };
        registerReceiver(broadcastReceiver,intentFilter);
    }

    public void turnBluetoothOn(View view){
        if(!bluetoothAdapter.isEnabled()){
            bluetoothAdapter.enable();
            Toast.makeText(this,"Bluetooth attivato",Toast.LENGTH_SHORT).show();
        }
    }

    public void turnBluetoothOff(View view){
        if(bluetoothAdapter.isEnabled()){
            bluetoothAdapter.disable();
            Toast.makeText(this,"Bluetooth disattivato",Toast.LENGTH_SHORT).show();
        }
    }

    public void scanDevices(View view){
        turnBluetoothOn(null);
        if(bluetoothAdapter.isDiscovering())
            bluetoothAdapter.cancelDiscovery();
        Toast.makeText(this, "Scansione " + (bluetoothAdapter.startDiscovery()?"":"non") + " avviata.", Toast.LENGTH_SHORT).show();
        printDevices();
    }

    String toStamp = "";
    private void printDevices(){
        bluetoothDevicesBounded = bluetoothAdapter.getBondedDevices();
        if(!bluetoothDevicesBounded.isEmpty()){
            toStamp = "Dispositivi associati:\n";
            for(BluetoothDevice b : bluetoothDevicesBounded){
                toStamp += b.getName() + " | " + b.getAddress() + "\n";
            }
            tvBoundedDevices.setText(toStamp + "");
        }
        if(!bluetoothDevicesFound.isEmpty()){
            toStamp = "Dispositivi trovati:\n";
            for(BluetoothDevice b : bluetoothDevicesFound){
                toStamp += b.getName() + " | " + b.getAddress() + "\n";
            }
            tvDiscoveredDevices.setText(toStamp + "");
        }
    }
}