@Override
    public Class<?> getColumnClass(int columnIndex) {
	switch (columnIndex) {
	    case 0: // ID
		return Integer.class;
	    case 1: // Firstname
		return String.class;
	    case 2: // Lastname
		return String.class;
	    case 3: // Birth
		return Date.class;
	    case 4: // Email
		return String.class;
	    default:
		throw new IllegalArgumentException("columnIndex");
	}
    }