Demo

Overview

1. Declare permissions in Manifest.

2. Request permissions at runtime.

3. Get a handle to the default local BluetoothAdapter.

4. Start the remote device discovery process and register BroadcastReceiver.

5. Get Bluetooth devices from BroadcastReceiver.

6. Unregister BroadcastReceiver.

How to build

Step 1. Declare permissions in Manifest.

<!-- AndroidManifest.xml -->

<manifest ...">

    ...
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <!-- If your app targets Android 9 or lower, you can declare
         ACCESS_COARSE_LOCATION instead. -->
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    ...

</manifest>

Step 2. Request permissions at runtime.

/* MainActivity.java */

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

    ...
    // check for permissions
    if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_DENIED) {
        String[] permission = {Manifest.permission.ACCESS_FINE_LOCATION};
        requestPermissions(permission, PERMISSION_CODE);
    } else {
        checkBluetoothAdapter();
    }
    ...
}

Step 3. Get a handle to the default local BluetoothAdapter.

/* MainActivity.java */

private void checkBluetoothAdapter() {
    mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    if (mBluetoothAdapter == null) {
        Toast.makeText(this, "Device does not support Bluetooth", Toast.LENGTH_SHORT).show();
    } else {
        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        } else {
            startBroadcastIntent();
        }
    }
}

Step 4. Start the remote device discovery process and register BroadcastReceiver.

/* MainActivity.java */

public void startBroadcastIntent() {
    // start discovery
    mBluetoothAdapter.startDiscovery();
    // register broadcast receiver and listen to specific "ACTION_FOUND" request
    IntentFilter filter = new IntentFilter();
    filter.addAction(BluetoothDevice.ACTION_FOUND);
    this.registerReceiver(receiver, filter);
}

Step 5. Get Bluetooth devices from BroadcastReceiver.

/* MainActivity.java */

private final BroadcastReceiver receiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        // if remote bluetooth device found
        if (BluetoothDevice.ACTION_FOUND.equals(action)) {

            //  receive related contents of new bluetooth device
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);

            if (device != null) {
                // device name and MAC address
                String deviceName = device.getName();
                String deviceHardwareAddress = device.getAddress(); // MAC address
                Log.d("BTDevice",deviceName + deviceHardwareAddress);

                // add this info to list
                mDeviceList.add(device.getName() + "\n" + device.getAddress());

                // set contents into ListView
                listView.setAdapter(new ArrayAdapter<>(context,
                        android.R.layout.simple_list_item_1, mDeviceList));
            }
        }
    }
};

Step 6. Unregister BroadcastReceiver.

/* MainActivity.java */

@Override
protected void onDestroy() {
    super.onDestroy();
    // unregister broadcast receiver
    unregisterReceiver(receiver);
}

Source code

https://github.com/tuttelikz/BluetoothSimple