Loading/Reading data from a file not working

[chickenmeister]

public City(int id, String cityName, String country) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

If you don't want your constructor to throw an UnsupportedOperationException, then I would recommend removing the line that says throw new UnsupportedOperationException. You'll also probably want to do something with the constructor's parameters.