private PDFObject popObject() throws PDFParseException {
  Object obj=stack.pop();
  if (!(obj instanceof PDFObject)) {
    throw new PDFParseException("Expected a reference here: " + obj.toString());
  }
  return (PDFObject)obj;
}

private PDFObject popObject ( ) throws PDFParseException { Object obj = stack . pop ( ) ; if ( ! ( obj instanceof PDFObject ) ) { throw new PDFParseException ( "Expected a reference here: " + obj . toString ( ) ) ; } return ( PDFObject ) obj ; }
pop a pdfobject off the stack .
