Show notifications on Screen in Android

i am using this code for sending local notifications

mNotificationManager = (NotificationManager)
                getSystemService(Context.NOTIFICATION_SERVICE);

        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                i, PendingIntent.FLAG_ONE_SHOT);

        NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(this)
                        .setSmallIcon(R.drawable.ic_launcher)
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher))
                        .setContentTitle(title)
                        .setDefaults(Notification.DEFAULT_SOUND)
                        .setStyle(new NotificationCompat.BigTextStyle()
                                .bigText(msg))
                        .setContentText(msg);

        mBuilder.setContentIntent(contentIntent);
        mNotificationManager.notify((int)value, mBuilder.build());

However they display on status bar if phone screen is lock by sliding. I want to show the push notifications on top of screen like whatsapp, facebook, sms messages etc.

How can I make this possible?