updating the views of a RemoteView during media playback

I'm using the following code to generate a mediaPlayer notification:

package com.app1.notificationtemplate;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.content.Context;
import android.content.Intent;
import android.os.Build;
import android.os.Handler;
import android.widget.RemoteViews;
import androidx.core.app.NotificationCompat;
public class NotificationGenerator {
public static final int  NOTIFICATION_ID_OPEN_ACTIVITY = 9;
public static final String NOTIFY_PREVIOUS = "com.a.b.previous";
public static final String NOTIFY_DELETE = "com.a.b.delete";
public static final String NOTIFY_PAUSE = "com.a.b.pause";
public static final String NOTIFY_PLAY = "com.a.b.play";
public static final String NOTIFY_NEXT = "com.a.b.next";
public static void openActivityNotificaton(Context context) {
NotificationCompat.Builder nc = new NotificationCompat.Builder(context,
MainActivity.channelID);
NotificationManager nm = (NotificationManager)context.getSystemService(Context.NOTIFICATION_SERVICE);
Intent notifyIntent = new Intent(context, MainActivity.class);
notifyIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
nc.setContentIntent(pendingIntent);
nc.setSmallIcon(R.mipmap.ic_launcher);
nc.setAutoCancel(true);
nc.setContentTitle("Notification Demo");
nc.setContentText("Click please");
nm.notify(NOTIFICATION_ID_OPEN_ACTIVITY, nc.build());
}
public static void customBigNotification(Context context){
final RemoteViews expandedView = new RemoteViews(context.getPackageName(), R.layout.big_notification);
NotificationCompat.Builder nc = new NotificationCompat.Builder(context, MainActivity.channelID);
NotificationManager nm = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
Intent notifyIntent = new Intent(context, MainActivity.class);
notifyIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, notifyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
nc.setContentIntent(pendingIntent);
nc.setSmallIcon(R.drawable.play);
nc.setAutoCancel(true);
nc.setCustomBigContentView(expandedView);
nc.setContentTitle("MusicPlayer");
nc.setPriority(NotificationCompat.PRIORITY_MAX);
nc.setContentText("Control AUdio");
//expandedView.setTextViewText(R.id.text_song_name,"Adele");
setListeners(expandedView, context);
Notification notification = nc.build();
notification.flags = NotificationCompat.FLAG_ONGOING_EVENT|NotificationCompat.FLAG_FOREGROUND_SERVICE
| NotificationCompat.FLAG_NO_CLEAR|NotificationCompat.FLAG_BUBBLE ;
AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
nm.notify("newNotif", 1, nc.build());
}
public  static void setListeners(RemoteViews view, Context context){
Intent previous = new Intent(NOTIFY_PREVIOUS);
Intent delete = new Intent(NOTIFY_DELETE);
Intent pause = new Intent(NOTIFY_PAUSE);
Intent next = new Intent(NOTIFY_NEXT);
Intent play = new Intent(NOTIFY_PLAY);
PendingIntent pPrevious = PendingIntent.getBroadcast(context, 0,
previous, PendingIntent.FLAG_UPDATE_CURRENT);
view.setOnClickPendingIntent(R.id.btnPrevious, pPrevious);
PendingIntent pDelete = PendingIntent.getBroadcast(context, 0,
delete, PendingIntent.FLAG_UPDATE_CURRENT);
view.setOnClickPendingIntent(R.id.btnDelete, pDelete);
PendingIntent pPause = PendingIntent.getBroadcast(context, 0,
pause, PendingIntent.FLAG_UPDATE_CURRENT);
view.setOnClickPendingIntent(R.id.btnPause, pPause);
PendingIntent pPlay = PendingIntent.getBroadcast(context, 0,
play, PendingIntent.FLAG_UPDATE_CURRENT);
view.setOnClickPendingIntent(R.id.btnPlay, pPlay);
PendingIntent pNext = PendingIntent.getBroadcast(context, 0,
next, PendingIntent.FLAG_UPDATE_CURRENT);
view.setOnClickPendingIntent(R.id.btnNext, pNext);
}
}    

I have custom notification views (RemoteViews) setup for the notification as well.

but, when I click play, I'm not sure how to update the play view to a pause view. Currently, I'm just setting the visibility of the play button to gone. But, is turning on and off the visibility turnwise the only option? And how do I do that anyways(the tutorial I've followed doesn't really show this). But, I think it'd be better if we could replace the image in the button which would avoid possible blinking or flickering. I've also gotta update the Remote view's artist and song Title name, but have no idea to do so. Please tell me how to update views in the RemoteView according to user interaction

Also, to communicate from the notification to the Service is using Broadcasts the only option? What other options do I have?

You need to create a new notification with the updated data and use NotificationManager to update it. No need to start service again. You have a running foreground service, all you have to do is update your UI via notify.

So in your Broadcast Receiver call your openActivityNotificaton() function with updated data, according to what view was clicked inside the notification. You can have one Receiver with a unique action for each view click, and update notification accordingly. I tested and it does not cause a blink, the notification is updated smoothly.

The code for your Receiver would be something like this:

const val NOTIFICATION_TITLE_INTENT_ACTION = "notification_title_intent_action"
const val NOTIFICATION_ARROW_INTENT_ACTION = "notification_arrow_intent_action"
class NotificationInteractionReceiver : BroadcastReceiver() {
private lateinit var notificationsFactory: NotificationFactory
override fun onReceive(context: Context, intent: Intent) {
notificationsFactory = NotificationFactory(context)
// Update title according to what button was clicked
val newTitle = when (intent.action) {
NOTIFICATION_TITLE_INTENT_ACTION -> "title clicked"
else -> "arrow clicked"
}
// Pass new title to class responsible for showing notification
notificationsFactory.showNotification(context, s)
}
companion object {
fun getIntent(context: Context, action: String): Intent {
val intent = Intent(context, NotificationInteractionReceiver::class.java).apply {
flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}
intent.action = action
return intent
}
}
}