android MediaSession setActive(false) not work

I use MediaSession to respond to headset media buttons, and want to stop the sound when activity is paused. I also want to make the headset media buttons not active when activity is paused.

From the android documentation, it said the setActive method is use to "set if this session is currently active and ready to receive commands". But it not worked, I can still use head resume the music when activity is paused. Do I misunderstand the function of this method?

My code is as followed:

@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
class MainActivity : AppCompatActivity() {

private lateinit var mediaSession: MediaSession
private var mediaPlayer: MediaPlayer? = null

public override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    setContentView(R.layout.activity_main)

    mediaPlayer = MediaPlayer.create(this, R.raw.lapple)
    mediaPlayer?.isLooping = true
    mediaPlayer?.start()
    // Create a MediaSessionCompat

    mediaSession = MediaSession(this, "test_log").apply {

        // Enable callbacks from MediaButtons and TransportControls
        setFlags(MediaSession.FLAG_HANDLES_MEDIA_BUTTONS or MediaSession.FLAG_HANDLES_TRANSPORT_CONTROLS)

        // Do not let MediaButtons restart the player when the app is not visible
        setMediaButtonReceiver(null)

        // Set an initial PlaybackState with ACTION_PLAY, so media buttons can start the player
        val stateBuilder = PlaybackState.Builder()
            .setActions(PlaybackState.ACTION_PLAY or PlaybackState.ACTION_PAUSE or PlaybackState.ACTION_PLAY_PAUSE)
        setPlaybackState(stateBuilder.build())

        // MySessionCallback has methods that handle callbacks from a media controller
        setCallback(object : MediaSession.Callback() {
            override fun onPlay() {
                Toast.makeText(
                    this@MainActivity,
                    "${this@MainActivity.hashCode()}: onPlay",
                    Toast.LENGTH_SHORT
                ).show()
                mediaPlayer?.start()
            }

            override fun onPause() {
                mediaPlayer?.pause()
                Toast.makeText(
                    this@MainActivity,
                    "${this@MainActivity.hashCode()}: onPause",
                    Toast.LENGTH_SHORT
                ).show()
            }

        })
    }

    mediaSession.isActive = true

    //mediaController = MediaController(this, mediaSession.sessionToken)

}

override fun onPause() {
    super.onPause()
    mediaSession.isActive = false
    mediaPlayer?.pause()
}

override fun onResume() {
    super.onResume()
    mediaSession.isActive = true
    mediaPlayer?.start()
}

override fun onDestroy() {
    mediaPlayer?.release()
    super.onDestroy()
}

fun newActivity(view: View) {
    startActivity(Intent(this, MainActivity::class.java))
}
}

The documentation says:

> Set if this session is currently active and ready to receive commands. If set to false your session's controller may not be discoverable. You must set the session to active before it can start receiving media button events or transport commands.

It does not say that you should set it to false to stop receiving commands. I guess if the controller is already discovered, the value doesn't matter anymore.

So instead you should use release or setCallback(null) according to this documentation.

Just for the record: For me setCallback(null) was not working, since I by mistake added two MEDIA_BUTTON.BroadcastReceiver to Manifest.xml. This somehow started the Service in the background without attached Activity

 <application>

        <service
            android:name=".service.MyService">

            <intent-filter>
                <action android:name="android.intent.action.MEDIA_BUTTON" />
            </intent-filter>

        </service>

        <!-- this was the stupid receiver. DO NOT DO IT ;-) -->
        <receiver android:name="androidx.media.session.MediaButtonReceiver">
            <intent-filter>
                <action android:name="android.intent.action.MEDIA_BUTTON" />
            </intent-filter>
        </receiver>
    </application>

</details>