Notification channels enable us app developers to group our notifications into groups—channels—with the user having the ability to modify notification settings for the entire channel at once.In Android O this feature is introduced.Right now it is available developers preview.
| Method | Description | 
|---|---|
| IMPORTANCE_MAX | unused | 
| IMPORTANCE_HIGH | shows everywhere, makes noise and peeks | 
| IMPORTANCE_DEFAULT | shows everywhere, makes noise, but does not visually intrude | 
| IMPORTANCE_LOW | shows everywhere, but is not intrusive | 
| IMPORTANCE_MIN | only shows in the shade, below the fold | 
| IMPORTANCE_NONE | a notification with no importance; does not show in the shade |