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class PasswordManager {

  public static void changePassword() {
    FileInputStream fin = openPasswordFile();
    if (fin == null) {
      // no password file; handle error
    }

    // test old password with password in file contents; change password
  }

  private static FileInputStream openPasswordFile() {
    final String password_file = "password";
    final FileInputStream fin[] = { null };
    AccessController.doPrivileged( new PrivilegedActionPrivilegedAction<Void>() {
        public ObjectVoid run() {
          try {
            // Sensitive action; can't be done outside
            // doPrivileged() block
            fin[0] = new FileInputStream(password_file);
          } catch (FileNotFoundException x) {
            // report to handler
          }
          return null;
        }
      });
    return fin[0];
  }
}