Android how to get all external directory files including sd card

file.java

public List<File> getExternalDirectoryRoots(Context context) {
    File[] externalFilesDirs = ContextCompat.getExternalFilesDirs(context, null);

    List<File> externalDirectories = new ArrayList<>();

    Set<String> stringSet = new HashSet<>();

    for (File file : externalFilesDirs) {
        String[] split = file.getAbsolutePath().split("/");
        if (split.length > 1) {
            stringSet.add(split[1]);
        }
    }

    for (String str : stringSet) {
        externalDirectories.add(new File(str));
    }

    return externalDirectories;
}