public synchronized boolean enter(CnATreeElement obj) throws TransactionAbortedException {
  if (aborted) {
    throw new TransactionAbortedException();
  }
  visited.add(obj);
  if (this.initiator != null) {
    return false;
  }
  this.initiator=obj;
  aborted=false;
  return true;
}

public synchronized boolean enter ( CnATreeElement obj ) throws TransactionAbortedException { if ( aborted ) { throw new TransactionAbortedException ( ) ; } visited . add ( obj ) ; if ( this . initiator != null ) { return false ; } this . initiator = obj ; aborted = false ; return true ; }
the given objects enters the transaction .
