title: Android 9 Api 28 Notification not showing
body: <p>I'm trying to show notification but it's not working for both Oreo and Pie version.</p>
  
  <p>It's working in kitkat version.</p>
  
  <p>I tried all the possible condition i can do, i don't know what else i'm missing here</p>
  
  <p>Here is my code:</p>
  
  <pre><code>String idChannel = "my_channel_01";
          Intent mainIntent;
          mainIntent = new Intent(ChecklistOptionActivity.this, CashCountOptionActivity.class);
  
          PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, mainIntent, 0);
  
          NotificationManager mNotificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
  
          NotificationChannel mChannel = null;
          // The id of the channel.
  
          int importance = NotificationManager.IMPORTANCE_HIGH;
  
          NotificationCompat.Builder builder = new NotificationCompat.Builder(context);
          builder.setContentTitle(context.getString(R.string.app_name))
                  .setSmallIcon(R.drawable.bc_icon)
                  .setContentIntent(pendingIntent)
                  .setContentText("Test");
  
          if (Build.VERSION.SDK_INT &gt;= Build.VERSION_CODES.O) {
              mChannel = new NotificationChannel(idChannel, context.getString(R.string.app_name), importance);
              // Configure the notification channel.
              mChannel.setDescription("Test");
              mChannel.enableLights(true);
              mChannel.setLightColor(Color.RED);
              mChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
              mNotificationManager.createNotificationChannel(mChannel);
          } else {
              builder.setContentTitle(context.getString(R.string.app_name))
                      .setPriority(NotificationCompat.PRIORITY_HIGH)
                      .setColor(ContextCompat.getColor(context, R.color.colorBlue))
                      .setVibrate(new long[]{100, 250})
                      .setLights(Color.YELLOW, 500, 5000)
                      .setAutoCancel(true);
          }
          mNotificationManager.notify(1, builder.build());
  </code></pre>