private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
  in.defaultReadObject();
  if (choiceLimits.length != choiceFormats.length) {
    throw new InvalidObjectException("limits and format arrays of different length.");
  }
}

private void readObject ( ObjectInputStream in ) throws IOException , ClassNotFoundException { in . defaultReadObject ( ) ; if ( choiceLimits . length != choiceFormats . length ) { throw new InvalidObjectException ( "limits and format arrays of different length." ) ; } }
after reading an object from the input stream , do a simple verification to maintain class invariants .
