Is it possible to cancel/stop a download started using DownloadManager?

You can cancel downloads via DownloadManager by calling its remove(long...) method. For this you need the ID of the download. From my experience there basically are two reliable ways how to get it:

1. Remember the return value of enqueue(DownloadManager.Request) method.
2. Query the DownloadManager for downloads via query(DownloadManager.Query) method. Then retrieve the IDs from the returned Cursor, they are stored in the column named DownloadManager.COLUMN_ID.

Broadcast Receiver

From my experience, it is not reliable to retrieve download ID via BroadcastReceiver for action android.intent.action.DOWNLOAD_NOTIFICATION_CLICKED (though the broadcast is always sent).

1. Getting download IDs from extra DownloadManager. EXTRA_NOTIFICATION_CLICK_DOWNLOAD_IDS does not work properly. On some devices, it always return null. If it returns something on some devices, it is the ID of the download started first. And if the first download is finished/canceled, it returns null for notification of the remaining downloads.
2. Getting a value from extra DownloadManager.EXTRA_DOWNLOAD_ID does not work for this action.

Getting ID in broadcast for action android.intent.action.DOWNLOAD_COMPLETE seems reliable. You have to get it from extra DownloadManager.EXTRA_DOWNLOAD_ID. Note that the broadcast is sent not only for completed download, it is also sent when you cancel download calling remove().

Note: Downloads are sometimes grouped in one notification, sometimes create multiple notifications. I wasn't able to figure out the conditions when notifications do and do not group. It seems to depend on many factors like OS version, device, download title, ... and in general seems rather unpredictable.

Note: I've tested whether you can cancel other app's download and it doesn't seem so. Even though that the IDs are database IDs that are unique across all apps. Calling remove() does not cancel another app's download.

If you are looking how to stop the download, then I am sure you know how to download data through URL.
I am hopping you are familiar with point 1, point 2 and point 3, and your solution is point 4.

1. private var mgr: DownloadManager? = null
2. private var enqueue: Long? = null
3. enqueue = mgr?.enqueue(request)
4. mgr?.remove(enqueue!!)