public void flushAllPages() throws 
    HashOperationException, 
    PageUnpinnedException,  
    PagePinnedException, 
    PageNotFoundException,
    BufMgrException,
    IOException {
      
      // send to the private method with the common coe for all flush methods
      PageId pageId = new PageId(INVALID_PAGE);
      privFlushPages(pageId ,1); 
    } // end flushAllPages()