Android - When are the default folders (DCIM, Downloads, etc.) in the sdcard created?

Question

I am building a custom Marshmallow Android version, and I would like to add some files to the sdcard on first boot - specifically, I want them to be created at the same time DCIM, Downloads, Ringtones, etc. are being created.

When is the default folder structure created?

Answer 1

While in theory you can find this kind of thing by doing a full text search for a string, that can take a while on a many-gigabyte codebase, so it helps to have some good guesses for where to look.

It turns out that the default folders are created in MediaProvider.Java located in packages/providers/MediaProvider

Depending on the specific version of Android the method may be called ensureDefaultFolders() or createDefaultFolders() or something else. For example:

    private static final String[] sDefaultFolderNames = {
        Environment.DIRECTORY_MUSIC,
        Environment.DIRECTORY_PODCASTS,
        Environment.DIRECTORY_RINGTONES,
        Environment.DIRECTORY_ALARMS,
        Environment.DIRECTORY_NOTIFICATIONS,
        Environment.DIRECTORY_PICTURES,
        Environment.DIRECTORY_MOVIES,
        Environment.DIRECTORY_DOWNLOADS,
        Environment.DIRECTORY_DCIM,
    };
    /**
     * Ensure that default folders are created on mounted primary storage
     * devices. We only do this once per volume so we don't annoy the user if
     * deleted manually.
     */
    private void ensureDefaultFolders(DatabaseHelper helper, SQLiteDatabase db)