MediaRouteActionProvider

public class MediaRouteActionProvider extends ActionProvider

<menu xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/media_route_menu_item"
        android:title="@string/media_route_menu_title"
        app:showAsAction="always"
        app:actionProviderClass="androidx.mediarouter.app.MediaRouteActionProvider"/>
</menu>

public class MyActivity extends AppCompatActivity {
    private MediaRouter mRouter;
    private MediaRouter.Callback mCallback;
    private MediaRouteSelector mSelector;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mRouter = MediaRouter.getInstance(this);
        mSelector = new MediaRouteSelector.Builder()
                .addControlCategory(MediaControlIntent.CATEGORY_LIVE_AUDIO)
                .addControlCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK)
                .build();
        mCallback = new MyCallback();
    }

    // Add the callback on start to tell the media router what kinds of routes
    // the application is interested in so that it can try to discover suitable ones.
    public void onStart() {
        super.onStart();

        mediaRouter.addCallback(mSelector, mCallback,
                MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY);

        MediaRouter.RouteInfo route = mediaRouter.updateSelectedRoute(mSelector);
        // do something with the route...
    }

    // Remove the callback flag CALLBACK_FLAG_REQUEST_DISCOVERY on stop by calling
    // addCallback() again in order to tell the media router that it no longer
    // needs to invest effort trying to discover routes of these kinds for now.
    public void onStop() {
        mRouter.addCallback(mSelector, mCallback, /* flags= */ 0);

        super.onStop();
    }

    // Remove the callback when the activity is destroyed.
    public void onDestroy() {
        mRouter.removeCallback(mCallback);

        super.onDestroy();
    }

    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        getMenuInflater().inflate(R.menu.sample_media_router_menu, menu);

        MenuItem mediaRouteMenuItem = menu.findItem(R.id.media_route_menu_item);
        MediaRouteActionProvider mediaRouteActionProvider =
                (MediaRouteActionProvider)MenuItemCompat.getActionProvider(mediaRouteMenuItem);
        mediaRouteActionProvider.setRouteSelector(mSelector);
        return true;
    }

    private final class MyCallback extends MediaRouter.Callback {
        // Implement callback methods as needed.
    }
}