Java小程序运费计算器，如果低于100美元，不确定如何添加免费送货

Java applet shipping calculator, unsure how to add free shipping if under $100

我在课堂上做一个编码作业。它是一个虚构的蜡烛网站的基本运费计算器。客户会输入他们的销售总额，然后选择他们想要的运输水平，它会说成本。选项包括隔夜、优先或标准。一夜之间，优先权是固定成本，所以这很容易。但如果订单低于100美元，则标准价格为7.95美元；如果订单高于100美元，则标准价格为0美元。

我已经为订单总额创建了一个文本字段，并为过夜、优先级和标准创建了复选框。不出一个小奇迹(我在这门课上很差劲)，我这里实际上有一个功能性的小程序，只是我不知道如何计算订单总额大于100美元=免费送货。

我觉得我需要创建一个case 4，其中shipping=total+0，但我不确定如何创建代码4，或者在哪里添加了一个true/false或if..else语句来实现这一点。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.text.DecimalFormat;

public class ShippingApplet extends Applet implements ItemListener
{
int shipSpeed;
double dollars, answer;

Label headLabel = new Label ("CandleLine--Candles Online");

Label promptLabel = new Label("Please enter the total dollar amount of your order:");
TextField totalField = new TextField(20);

Label hiddenLabel = new Label("");

Label codeLabel = new Label ("Please choose your method of shipping:");

CheckboxGroup codeGroup = new CheckboxGroup();
Checkbox overnightBox = new Checkbox("Priority(Overnight)",false,codeGroup);
Checkbox expressBox = new Checkbox("Express (2 business days)",false,codeGroup);
Checkbox standardBox = new Checkbox("Standard (3 to 7 business days)",false,codeGroup);
Checkbox hiddenBox = new Checkbox("",true,codeGroup);

Label outputLabel=new Label("We guarantee on time delivery, or your money back.");

public void init()
{
setBackground(Color.cyan);
setForeground(Color.black);
add(headLabel);
add(promptLabel);
add(totalField);
totalField.requestFocus();
totalField.setForeground(Color.black);
add(hiddenLabel);
add(codeLabel);
add(overnightBox);
overnightBox.addItemListener(this);
add(expressBox);
expressBox.addItemListener(this);
add(standardBox);
standardBox.addItemListener(this);
add(outputLabel);
}

public void itemStateChanged(ItemEvent choice)
{

try
{
dollars = getTotal();
shipSpeed = getCode();
answer = getShip(dollars,shipSpeed);
output(answer, dollars);
}

catch(NumberFormatException e)
{
outputLabel.setText("You must enter a dollar amount greater than zero.");
hiddenBox.setState(true);
totalField.setText("");
totalField.requestFocus();
}
}
public double getTotal()
{
double total = Double.parseDouble(totalField.getText());

if (total <= 0) throw new NumberFormatException();

return total;
}

public int getCode()
{
int code = 0;
if (overnightBox.getState()) code = 1;
else
if (expressBox.getState()) code = 2;
else
if (standardBox.getState()) code = 3;
return code;
}

public double getShip(double total, int code)
{
double shipping = 0.0;
switch(code)
{
case 1:
shipping = total + 16.95;
break;

case 2:
shipping = total + 13.95;
break;

case 3:
shipping = total + 7.95;
break;
}
return shipping;
}
public void output(double shipping, double total)
{
DecimalFormat twoDigits = new DecimalFormat("$#,000.00");
outputLabel.setText("Your order of" + twoDigits.format(total) +" plus shipping totals to: " + twoDigits.format(shipping));
}

}