java.lang.IllegalStateException: Method call should happen from the main thread

[Shajeel-Afzal]

I am trying the following code to show Custom Notification but the app is crashing giving java.lang.IllegalStateException: Method call should happen from the main thread.

PendingIntent pendingIntent;
        String url = data.get(CommonConsts.NOTIFICATION_KEY_URL);
        String thumbUrl = data.get(CommonConsts.THUMB_URL_KEY);

        Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));

        // Use TaskStackBuilder to build the back stack and get the PendingIntent
        pendingIntent =
                TaskStackBuilder.create(this)
                        // add all of DetailsActivity's parents to the stack,
                        // followed by DetailsActivity itself
                        .addNextIntentWithParentStack(browserIntent)
                        .getPendingIntent(0, PendingIntent.FLAG_ONE_SHOT);

        Custom mLoad = null;
        if (pendingIntent != null) {
            mLoad = PugNotification.with(getBaseContext()).load()
                    .smallIcon(R.mipmap.ic_launcher)
                    .autoCancel(true)
                    .largeIcon(R.mipmap.ic_launcher)
                    .title(title == null ? this.getString(R.string.app_name) +
                            " Alert" : title)
                    .message(messageBody)
                    .bigTextStyle(messageBody, messageBody)
                    .priority(Notification.PRIORITY_MAX)
                    .flags(Notification.DEFAULT_ALL)
                    .when(1)
                    .button(R.drawable.ic_chrome_reader_mode_black_18dp, getString(R.string.read_more), pendingIntent)
                    .click(pendingIntent)
                    .custom()
                    .setImageLoader(new ImageLoader() {
                        @Override
                        public void load(String uri, OnImageLoadingCompleted onCompleted) {
                            viewTarget = getViewTarget(onCompleted);
                            Picasso.with(getBaseContext()).load(uri).into(viewTarget);
                        }

                        @Override
                        public void load(int imageResId, OnImageLoadingCompleted onCompleted) {

                        }
                    })
                    .setPlaceholder(R.drawable.pugnotification_ic_placeholder)
                    .background(thumbUrl);
        }

        if (mLoad != null) {
            mLoad.build();
        }

Complete Exception:
Process: psl99.com.pakistan_super_league, PID: 19021
java.lang.IllegalStateException: Method call should happen from the main thread. at br.com.goncalves.pugnotification.notification.Custom.build(Custom.java:119) at psl99.com.pakistan_super_league.services.MyFirebaseMessagingService.showNewsArticleNotification(MyFirebaseMessagingService.java:276) at psl99.com.pakistan_super_league.services.MyFirebaseMessagingService.sendNotification(MyFirebaseMessagingService.java:150)
atpsl99.com.pakistan_super_league.services.MyFirebaseMessagingService.onMessageReceived(MyFirebaseMessagingService.java:111)
at com.google.firebase.messaging.FirebaseMessagingService.handleIntent(Unknown Source)
at com.google.firebase.iid.zzc.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:762)