String[] choices = { "1000", "1100", "1200", "1300", "1400", "1500",
                                "1600", "1700", "1800", "1900", "2000", "2100",
                                "2200", "2300", "2400", "2500", "2600", "2700"
                                "2800", "2900", "3000", "Electric Car", "Motorbike" };

        String input = (String) JOptionPane.showInputDialog(null, "Select engine size (in cc) or engine type",
        "Engine Size or Type Selector", JOptionPane.QUESTION_MESSAGE, null, choices, choices[0]);
        double taxAmount = 0;
        if (input == "1000")
        {
            taxAmount = 199;
        }
        else if (input == "1100")
        {
            taxAmount = 299;
        }
        else if (input == "1200")
        {
            taxAmount = 330;
        }
        else if (input == "1300")
        {
            taxAmount = 358;
        }
        else if (input == "1400")
        {
            taxAmount = 385;
        }
        else if (input == "1500")
        {
            taxAmount = 413;
        }
        else if (input == "1600")
        {
            taxAmount = 514;
        }
        else if (input == "1700")
        {
            taxAmount = 544;
        }
        else if (input == "1800")
        {
            taxAmount = 636;
        }
        else if (input == "1900")
        {
            taxAmount = 673;
        }
        else if (input == "2000")
        {
            taxAmount = 710;
        }

        else if (input == "2100")
        {
            taxAmount = 906;
        }

        else if (input == "2200")
        {
            taxAmount = 951;
        }
        else if (input == "2300")
        {
            taxAmount = 994;
        }
        else if (input == "2400")
        {
            taxAmount = 1034;
        }
        else if (input == "2500")
        {
            taxAmount = 1080;
        }
        else if (input == "2600")
        {
            taxAmount = 1294;
        }
        else if (input == "2700")
        {
            taxAmount = 1345;
        }
        else if (input == "2800")
        {
            taxAmount = 1391;
        }
        else if (input == "2900")
        {
            taxAmount = 1443;
        }
        else if (input == "3000")
        {
            taxAmount = 1494;
        }
        else if (input == "Electric Car")
        {
            taxAmount = 120;
        }
        else if (input == "Motorbike")
        {
            taxAmount = 88;
        }