How to detect Bluetooth state change using a broadcast receiver?

Question

I am trying to make an app that shows a toast when the device's Bluetooth turned on. I wanna do that even when my app is not running. So I should use a broadcast receiver, add some permissions, an intent-filter to android manifest and make a java class but I don't know the details.

What should I do? Which permissions should I use?

score 79 · Accepted Answer · edited Feb 02 '15 at 19:54

AS far as permissions go, to detect the state change of bluetooth you need to add this to your AndroidManifest.xml.

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

An example receiver would look like this, you add this code to where you want to handle the broadcast, for example an activity:

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

                if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
                    if(intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, -1) 
    == BluetoothAdapter.STATE_OFF)
    // Bluetooth is disconnected, do handling here
}

}

        };

To use the receiver, you need to register it. Which you can do as follows. I register the receiver in my main activity.

registerReceiver(this, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));

You could also decide to add all of it to your AndroidManifest.xml. This way you can make a special class for the receiver and handle it there. No need to register the receiver, just make the class and add the below code to the AndroidManifest

<receiver
        android:name=".packagename.NameOfBroadcastReceiverClass"
        android:enabled="true">
    <intent-filter>
        <action android:name="android.bluetooth.adapter.action.STATE_CHANGED"/>
    </intent-filter>
</receiver>

Should this receiver work if I close the app? Because it does not work. — Hilal, Jun 09 '19 at 04:02

Manikanta Ottiprolu · Answer 2 · 2014-12-10T10:22:20.370

23

You have to take following permission.

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

and you have to write this as your intent filter in receiver tag.

<action android:name="android.bluetooth.adapter.action.STATE_CHANGED" />

edited Dec 10 '14 at 10:22

answered Jul 22 '14 at 13:11

Manikanta Ottiprolu

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23

Nicola Gallazzi · Answer 3 · 2019-06-05T11:30:30.713

8

Unfortunately, for apps targeting api 26 or higher, manifest declared broadcast receivers don't work anymore (reference here: https://developer.android.com/guide/components/broadcast-exceptions), with some exceptions. android.bluetooth.adapter.action.STATE_CHANGED is not in that list.

For bluetooth, you can only listen for changes on:

ACTION_CONNECTION_STATE_CHANGED, ACTION_ACL_CONNECTED, ACTION_ACL_DISCONNECTED

edited Jun 05 '19 at 11:30

answered Jun 21 '18 at 13:33

Nicola Gallazzi

7,897
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you listed action connection state changed twice – behelit May 02 '19 at 23:54
so what is the workaround? Once i register with ACTION_CONNECTION_STATE_CHANGED , what should the intent return me in onReceive . Or is there another technique to perform the task – Faisal Jul 08 '19 at 11:12
You still can register your broadcast receiver at activity or fragment level, remember to unregister the receiver once its job is done – Nicola Gallazzi Jul 09 '19 at 06:38
1

Thanks. I had problems detecting a change from "Bluetooth on" to "Bluetooth off" due to these changes in API 26. Works like a charm when I register the receiver in MainApplikation.kt: registerBlootoothReceiver(){ val filter = IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED) bluetoothReceiver = BluetoothReceiver() registerReceiver(bluetoothReceiver, filter) } – Luigi_Papardelle Apr 25 '20 at 10:55

How to detect Bluetooth state change using a broadcast receiver?

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