How can I get the size of a folder on SD card in Android?

/**
 * Query the media store for a directory size
 *
 * @param context
 *     the application context
 * @param file
 *     the directory on primary storage
 * @return the size of the directory
 */
public static long getFolderSize(Context context, File file) {
  File directory = readlink(file); // resolve symlinks to internal storage
  String path = directory.getAbsolutePath();
  Cursor cursor = null;
  long size = 0;
  try {
    cursor = context.getContentResolver().query(MediaStore.Files.getContentUri("external"),
        new String[]{MediaStore.MediaColumns.SIZE},
        MediaStore.MediaColumns.DATA + " LIKE ?",
        new String[]{path + "/%"},
        null);
    if (cursor != null && cursor.moveToFirst()) {
      do {
        size += cursor.getLong(0);
      } while (cursor.moveToNext());
    }
  } finally {
    if (cursor != null) {
      cursor.close();
    }
  }
  return size;
}

/**
 * Canonicalize by following all symlinks. Same as "readlink -f file".
 *
 * @param file
 *     a {@link File}
 * @return The absolute canonical file
 */
public static File readlink(File file) {
  File f;
  try {
    f = file.getCanonicalFile();
  } catch (IOException e) {
    return file;
  }
  if (f.getAbsolutePath().equals(file.getAbsolutePath())) {
    return f;
  }
  return readlink(f);
}

File DCIM = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
long directorySize = getFolderSize(context, DCIM);
String formattedSize = Formatter.formatFileSize(context, directorySize);
System.out.println(DCIM + " " + formattedSize);