How do I change a string to a double type?

if((e.getSource() == jBook)) {
    String name = jlbName.getText();
    String date = jlbDateProduce.getText();
    String time = jr1.getText();
    int number = (Integer.parseInt(jtfNoOfTicket.getText().trim()));
    String total = jlbTotal.getText();
    String price = jlbPrice.getText();

    //Passing
    ticketReservation frame = new ticketReservation(
        name, date, time, price, total, String.valueOf(number));
}