void addTestClass(String classname){
  if (classname.length() > 0) {
    setOption("testclass",classname);
    classnames.add(classname);
  }
 else {
    throw new IllegalArgumentException("class name may not be empty string");
  }
}

void addTestClass ( String classname ) { if ( classname . length ( ) > 0 ) { setOption ( "testclass" , classname ) ; classnames . add ( classname ) ; } else { throw new IllegalArgumentException ( "class name may not be empty string" ) ; } }
adds a test class name to this option set .
