public void deleteUnused(){
  while (queue != null) {
    Reference<? extends Object> ref=queue.poll();
    if (ref == null) {
      break;
    }
    deleteFile(ref,null);
  }
}

public void deleteUnused ( ) { while ( queue != null ) { Reference < ? extends Object > ref = queue . poll ( ) ; if ( ref == null ) { break ; } deleteFile ( ref , null ) ; } }
delete all unused files now .
