How to implement Android Notification with overview like WhatsApp? -

i want implement notification overview when device in use whatsapp:

i know basic implementation way:

pendingintent pendingintent = pendingintent.getactivity(this, 0,      new intent(this, mainactivity.class), 0);  notification notification = new notification.builder(this)                 .setcontenttitle("title")                 .setcontenttext("message")                 .setsmallicon(r.drawable.ic_notif)                 .setcontentintent(mpendingintent)                 .build();  notificationmanager notificationmanager =      (notificationmanager) getsystemservice(notification_service); notificationmanager.notify(1, notification); 

but in case, don't have overview. have small icon in notification bar:

finaly, it's priority level:

notificationbuilder.setpriority(notification.priority_high);