I am using opentok to implement Voice chat app. Everything is working fine I am stuck when changing the audio loudspeaker to Headset mode. I have also tried to manually change the loudspeaker audio voice to my ear piece speaker, but did not work.

Here is my class

public class MainActivity extends AppCompatActivity implements Session.SessionListener, PublisherKit.PublisherListener {
    private static String API_KEY = "46066142";
    private static String SESSION_ID = "1_MX40NjA2NjE0Mn5-MTUxOTM2OTQ3NDczMH5VaDJXL0lUdHRYWkpUTzlRbEs5aVJSaU1-fg";
    private static String TOKEN = "T1==cGFydG5lcl9pZD00NjA2NjE0MiZzaWc9ZmE5N2IyMzExNTczYWM3NDRmYmUzNTNiNThkOWUzMDJmOTgxYWQ3MDpzZXNzaW9uX2lkPTFfTVg0ME5qQTJOakUwTW41LU1UVXhPVE0yT1RRM05EY3pNSDVWYURKWEwwbFVkSFJZV2twVVR6bFJiRXM1YVZKU2FVMS1mZyZjcmVhdGVfdGltZT0xNTE5MzcxMjUwJnJvbGU9cHVibGlzaGVyJm5vbmNlPTE1MTkzNzEyNTAuNzg1NDExODQyNDc1MjQ=";
    private static final int RC_VIDEO_APP_PERM = 124;
    private Session mSession;
    private FrameLayout mPublisherViewContainer;
    private FrameLayout mSubscriberViewContainer;
    private Publisher mPublisher;
    private Subscriber mSubscriber;

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

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {

        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        EasyPermissions.onRequestPermissionsResult(requestCode, permissions, grantResults, this);
    }

    @AfterPermissionGranted(RC_VIDEO_APP_PERM)
    private void requestPermissions() {
        String[] perms = { Manifest.permission.INTERNET, Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO,Manifest.permission.MODIFY_AUDIO_SETTINGS };
        if (EasyPermissions.hasPermissions(this, perms)) {
            // initialize view objects from your layout
            mPublisherViewContainer = (FrameLayout)findViewById(R.id.publisher_container);
            mSubscriberViewContainer = (FrameLayout)findViewById(R.id.subscriber_container);
            // initialize and connect to the session
            mSession = new Session.Builder(this, API_KEY, SESSION_ID).build();
            mSession.setSessionListener(this);
            mSession.connect(TOKEN);
        } else {
            EasyPermissions.requestPermissions(this, "This app needs access to your camera and mic to make video calls", RC_VIDEO_APP_PERM, perms);
        }
    }

    @Override
    public void onConnected(Session session) {
        mPublisher = new Publisher.Builder(this).audioTrack(true).build();
        mPublisher.setPublisherListener(this);
        mPublisher.cycleCamera();
        mPublisherViewContainer.addView(mPublisher.getView());
        mSession.publish(mPublisher);
    }

    @Override
    public void onDisconnected(Session session) {

    }

    @Override
    public void onStreamReceived(Session session, Stream stream) {
        if (mSubscriber == null) {
            mSubscriber = new Subscriber.Builder(this, stream).build();
            mSession.subscribe(mSubscriber);
            mSubscriberViewContainer.addView(mSubscriber.getView());
        }
    }

    @Override
    public void onStreamDropped(Session session, Stream stream) {
        if (mSubscriber != null) {
            mSubscriber = null;
            mSubscriberViewContainer.removeAllViews();
        }
    }

    @Override
    public void onError(Session session, OpentokError opentokError) {

    }

    @Override
    public void onStreamCreated(PublisherKit publisherKit, Stream stream) {

    }

    @Override
    public void onStreamDestroyed(PublisherKit publisherKit, Stream stream) {

    }

    @Override
    public void onError(PublisherKit publisherKit, OpentokError opentokError) {

    }

}

Libraries that i have used

implementation 'com.opentok.android:opentok-android-sdk:2.13.0'
implementation 'pub.devrel:easypermissions:0.4.0'

Solutions

Add this code to your onStreamCreated method

@Override
public void onStreamCreated(PublisherKit publisherKit, Stream stream) {
    AudioDeviceManager.getAudioDevice().setOutputMode(BaseAudioDevice.OutputMode.Handset);
}

After wasting my 4 days, I got my solution.I am answering my own question because maybe it helps someone rather than wasting his/her 4 days.I am answering my question only because I got the solution, my other question has no answer still, you can check.