Android Sample Code for Scanning

				
					import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "BluetoothScan";
    private static final int PERMISSION_REQUEST_CODE = 101;

    private BluetoothAdapter bluetoothAdapter;
    private Button scanButton;

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

        scanButton = findViewById(R.id.scanButton); // Assumes you have a button in your XML layout

        // Initialize Bluetooth Adapter
        BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        if (bluetoothManager != null) {
            bluetoothAdapter = bluetoothManager.getAdapter();
        }

        scanButton.setOnClickListener(v -> checkPermissionsAndScan());
    }

    // Create a BroadcastReceiver to listen for discovered devices
    private final BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            
            if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                // A device was found
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                
                if (device != null) {
                    // Check for permission before accessing name (Required for Android 12+)
                    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.BLUETOOTH_CONNECT) 
                            == PackageManager.PERMISSION_GRANTED || Build.VERSION.SDK_INT < Build.VERSION_CODES.S) {
                        
                        String deviceName = device.getName();
                        String deviceHardwareAddress = device.getAddress(); // MAC address
                        
                        Log.d(TAG, "Device Found: " + deviceName + " [" + deviceHardwareAddress + "]");
                        // TODO: Add the device details to a ListView or RecyclerView adapter here
                    }
                }
            } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                Log.d(TAG, "Scan finished.");
            }
        }
    };

    private void checkPermissionsAndScan() {
        if (bluetoothAdapter == null) {
            Log.e(TAG, "Device does not support Bluetooth");
            return;
        }

        // Determine required permissions based on Android version
        String[] permissions;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
            permissions = new String[]{Manifest.permission.BLUETOOTH_SCAN, Manifest.permission.BLUETOOTH_CONNECT};
        } else {
            permissions = new String[]{Manifest.permission.ACCESS_FINE_LOCATION};
        }

        // Request permissions if not already granted
        if (!hasPermissions(permissions)) {
            ActivityCompat.requestPermissions(this, permissions, PERMISSION_REQUEST_CODE);
        } else {
            startBluetoothDiscovery();
        }
    }

    private boolean hasPermissions(String... permissions) {
        for (String permission : permissions) {
            if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
        return true;
    }

    private void startBluetoothDiscovery() {
        // Safe check for Android 12+ runtime compliance
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED 
                && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
            return;
        }

        // If already discovering, cancel it first to restart cleanly
        if (bluetoothAdapter.isDiscovering()) {
            bluetoothAdapter.cancelDiscovery();
        }

        // Register for broadcasts when a device is discovered
        IntentFilter filter = new IntentFilter();
        filter.addAction(BluetoothDevice.ACTION_FOUND);
        filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
        registerReceiver(receiver, filter);

        // Start looking for devices (Asynchronous 12-second process)
        bluetoothAdapter.startDiscovery();
        Log.d(TAG, "Scanning started...");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // Unregister the runtime receiver to prevent memory leaks
        try {
            unregisterReceiver(receiver);
        } catch (IllegalArgumentException e) {
            Log.w(TAG, "Receiver was not registered or already unregistered.");
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == PERMISSION_REQUEST_CODE) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                startBluetoothDiscovery();
            } else {
                Log.e(TAG, "Permissions denied. Cannot scan for devices.");
            }
        }
    }
}