Manually add local file to the Downloads app

To manually add a file you need to use the DownloadManager class. I use the following to show a file in the Download app that I created locally.

DownloadManager downloadManager = (DownloadManager)mainActivity.getSystemService(mainActivity.DOWNLOAD_SERVICE);
downloadManager.addCompletedDownload(file.getName(), file.getName(), true, "application/json", file.getAbsolutePath(),file.length(),true);

This will make the file appear in the Downloads app on 6.0, even if the file was created locally.

Kotlin Equivalent of the above answer:

val downloadManager =   this.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
downloadManager.addCompletedDownload(file.getName(), file.getName(), true, "application/json", file.getAbsolutePath(),file.length(),true)