How to Get Notified in Android if a Bluetooth Device is Available?

Are you tired of constantly checking your Android device for available Bluetooth devices? Do you want to receive notifications whenever a device is in range? Look no further! In this article, we’ll take you on a step-by-step journey to get notified on Android when a Bluetooth device is available.

Understanding Bluetooth Device Discovery

Before we dive into the notification part, let’s quickly understand how Bluetooth device discovery works on Android.

When you enable Bluetooth on your Android device, it starts scanning for nearby devices. This process is called device discovery. During discovery, your device sends out inquiry packets to nearby devices, and they respond with their device information, such as name, address, and services offered. Your device then stores this information in a list, allowing you to choose which device to connect to.

Understanding Android’s Bluetooth API

Android provides a Bluetooth API that allows developers to access and manipulate Bluetooth functionality on a device. This API includes methods for device discovery, pairing, and connection management. To get notified when a Bluetooth device is available, we’ll utilize the following API methods:

• startDiscovery(): Initiates device discovery
• cancelDiscovery(): Cancels ongoing device discovery
• getBondedDevices(): Retrieves a list of paired devices
• registerReceiver(): Registers a BroadcastReceiver to receive device discovery results

Creating a Bluetooth Device Scanner

To get notified when a Bluetooth device is available, we need to create a Bluetooth device scanner app. This app will use the Android Bluetooth API to initiate device discovery, register a BroadcastReceiver to receive device discovery results, and notify the user when a device is found.

Step 1: Create a New Android Project

Open Android Studio and create a new project. Choose “Empty Activity” and name your project “BluetoothDeviceScanner”.

android {
    compileSdkVersion 29
    defaultConfig {
        applicationId "com.example.bluetoothdevicescanner"
        minSdkVersion 21
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

Step 2: Add Bluetooth Permission

In your AndroidManifest.xml file, add the following permission:

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

Step 3: Create a BroadcastReceiver

Create a new BroadcastReceiver class that will receive device discovery results:

public class BluetoothDeviceDiscoveryReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (action.equals(BluetoothDevice.ACTION_FOUND)) {
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            // Handle device discovery result
            Log.d("BluetoothDeviceScanner", "Device found: " + device.getName() + " (" + device.getAddress() + ")");
        }
    }
}

Step 4: Register the BroadcastReceiver

In your main activity, register the BroadcastReceiver:

private BluetoothDeviceDiscoveryReceiver receiver;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    receiver = new BluetoothDeviceDiscoveryReceiver();
    IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    registerReceiver(receiver, filter);
}

Step 5: Start Device Discovery

In your main activity, start device discovery:

private BluetoothAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    adapter = BluetoothAdapter.getDefaultAdapter();
    if (adapter != null) {
        if (adapter.isEnabled()) {
            startDiscovery();
        } else {
            // Handle Bluetooth disabled
        }
    } else {
        // Handle Bluetooth not supported
    }
}

private void startDiscovery() {
    adapter.startDiscovery();
}

Handling Device Discovery Results

Now that we have our BroadcastReceiver registered and device discovery started, let’s handle the device discovery results.

Step 1: Get Device Information

In your BroadcastReceiver, get the device information from the intent:

BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
String deviceAddress = device.getAddress();

Step 2: Check Device Availability

Check if the device is available by checking its bond state:

if (device.getBondState() == BluetoothDevice.BOND_BONDED) {
    // Device is paired, notify the user
    notifyUser(deviceName, deviceAddress);
} else {
    // Device is not paired, ignore
}

Step 3: Notify the User

Create a notification to inform the user that a device is available:

private void notifyUser(String deviceName, String deviceAddress) {
    NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    Notification notification = new NotificationCompat.Builder(this)
            .setContentTitle("Bluetooth Device Available")
            .setContentText("Device " + deviceName + " (" + deviceAddress + ") is available")
            .setSmallIcon(R.drawable.ic_bluetooth)
            .build();
    manager.notify(1, notification);
}

Optimizing Device Discovery

To optimize device discovery, we can implement the following strategies:

Strategy	Description
Limit device discovery duration	Limit device discovery to a specific duration to conserve battery life and reduce unnecessary scans.
Scan in intervals	Scan for devices at regular intervals to reduce the number of unnecessary scans.
Use a whitelist	Maintain a whitelist of known devices to ignore unknown devices and reduce false positives.

Conclusion

In this article, we’ve explored how to get notified on Android when a Bluetooth device is available. By using the Android Bluetooth API, we created a Bluetooth device scanner app that initiates device discovery, registers a BroadcastReceiver to receive device discovery results, and notifies the user when a device is found. We also discussed strategies to optimize device discovery, such as limiting device discovery duration, scanning in intervals, and using a whitelist.

By implementing these techniques, you can create a robust and efficient Bluetooth device scanner app that provides timely notifications to the user. Happy coding!

Related Articles:

• Android Bluetooth API
• BluetoothAdapter
• BluetoothDevice

Frequently Asked Question

Get notified when your Bluetooth device is available with these easy steps!