private String popString() throws PDFParseException {
  Object obj=stack.pop();
  if (!(obj instanceof String)) {
    throw new PDFParseException("Expected string here: " + obj.toString());
  }
 else {
    return (String)obj;
  }
}

private String popString ( ) throws PDFParseException { Object obj = stack . pop ( ) ; if ( ! ( obj instanceof String ) ) { throw new PDFParseException ( "Expected string here: " + obj . toString ( ) ) ; } else { return ( String ) obj ; } }
pop a string off the stack .
