android - Environment.getExternalStorageDirectory does not return the path to the removable storage

Question

As of API level 8, it seems Android has redefined what "external" storage is. Reading through http://developer.android.com/reference/android/os/Environment.html, attached to the documentation for getExternalStorageDirectory I see the comment: "don't be confused by the word 'external' here. This directory can better be thought as media/shared storage... In devices with multiple 'external' storage directories... , this directory represents the 'primary' external storage that the user will interact with."

My app writes files to the path obtained by getExternalStorageDirectory, and I've had users ask for an option to write to their removable SD card instead. I had always assumed that getExternalStorageDirectory returned the path to the removable SD card, but this is no longer true. How do I access the path to this SD card?

Answer 1

According to the source, getExternalStorageDirectory is implemented to return whatever is set as "external storage" in the device environment:

public static File getExternalStorageDirectory() {
    return EXTERNAL_STORAGE_DIRECTORY;
}

and EXTERNAL_STORAGE_DIRECTORY is:

private static final File EXTERNAL_STORAGE_DIRECTORY
        = getDirectory("EXTERNAL_STORAGE", "/sdcard");

static File getDirectory(String variableName, String defaultPath) {
    String path = System.getenv(variableName);
    return path == null ? new File(defaultPath) : new File(path);
}

In contrast, getExternalStoragePublicDirectory(String type) requires one of these strings:

DIRECTORY_MUSIC, DIRECTORY_PODCASTS, DIRECTORY_RINGTONES, DIRECTORY_ALARMS, DIRECTORY_NOTIFICATIONS, DIRECTORY_PICTURES, DIRECTORY_MOVIES, DIRECTORY_DOWNLOADS, or DIRECTORY_DCIM. May not be null.

so it is not meant to return the sd-card root.

An alternative:

Finally, getExternalStorageState() will return the filesystem mounted in /mnt/sdcard/. According to CommonsWare in this answer: Find an external SD card location, there is no way to directly get the external sdcard (if it even exist).

An alternative would be to check isExternalStorageRemovable () and give a manual option if it is false.