public boolean hasReceipt(String receipt_id){
synchronized (_receipts) {
    for (Iterator i=_receipts.iterator(); i.hasNext(); ) {
      String o=(String)i.next();
      if (o.equals(receipt_id))       return true;
    }
  }
  return false;
}

public boolean hasReceipt ( String receipt_id ) { synchronized ( _receipts ) { for ( Iterator i = _receipts . iterator ( ) ; i . hasNext ( ) ; ) { String o = ( String ) i . next ( ) ; if ( o . equals ( receipt_id ) ) return true ; } } return false ; }
checks to see if a receipt has come in .
