问题：
JavaJOptionpane GUI和elseif值[重复]
卫念
我的java程序有一个等式，它不能识别括号中的双精度值（double PropertyTax），因此可以在等式中使用它。有什么建议吗？谢谢
import javax.swing.JOptionPane;
import java.util.Scanner;
public class CSC212{
public static void main(String[] args){
Scanner in = new Scanner(System.in);
String State = JOptionPane.showInputDialog("Enter the location ex: CA, AZ, WA, ect...");
if(State == "AL")
{
double PropertyTax = 0.33;
}
else if(State == "AK")
{
double PropertyTax = 1.04;
}
else if(State == "AZ")
{
double PropertyTax = 0.72;
}
else if(State == "AR")
{
double PropertyTax = 0.52;
}
else if(State == "CA")
{
double PropertyTax = 0.74;
}
else if(State == "CO")
{
double PropertyTax = 0.6;
}
else if(State == "CT")
{
double PropertyTax = 1.63;
}
else if(State == "DE")
{
double PropertyTax = 0.43;
}
else if(State == "FL")
{
double PropertyTax = 0.97;
}
else if(State == "GA")
{
double PropertyTax = 0.83;
}
else if(State == "HI")
{
double PropertyTax = 0.26;
}
else if(State == "ID")
{
double PropertyTax = 0.69;
}
else if(State == "IL")
{
double PropertyTax = 1.73;
}
else if(State == "IN")
{
double PropertyTax = 0.85;
}
else if(State == "IA")
{
double PropertyTax = 1.29;
}
else if(State == "KS")
{
double PropertyTax = 1.01;
}
else if(State == "KY")
{
double PropertyTax = 0.72;
}
else if(State == "LA")
{
double PropertyTax = 0.18;
}
else if(State == "ME")
{
double PropertyTax = 1.09;
}
else if(State == "MD")
{
double PropertyTax = 0.87;
}
else if(State == "MA")
{
double PropertyTax = 1.04;
}
else if(State == "MI")
{
double PropertyTax = 1.05;
}
else if(State == "MN")
{
double PropertyTax = 1.05;
}
else if(State == "MS")
{
double PropertyTax = 0.52;
}
else if(State == "MO")
{
double PropertyTax = 0.91;
}
else if(State == "MT")
{
double PropertyTax = 0.83;
}
else if(State == "NE")
{
double PropertyTax = 1.76;
}
else if(State == "NV")
{
double PropertyTax = 0.84;
}
else if(State == "NH")
{
double PropertyTax = 1.86;
}
else if(State == "NJ")
{
double PropertyTax = 1.89;
}
else if(State == "NM")
{
double PropertyTax = 0.55;
}
else if(State == "NY")
{
double PropertyTax = 1.23;
}
else if(State == "NC")
{
double PropertyTax = 0.78;
}
else if(State == "ND")
{
double PropertyTax = 1.42;
}
else if(State == "OH")
{
double PropertyTax = 1.36;
}
else if(State == "OK")
{
double PropertyTax = 0.74;
}
else if(State == "OR")
{
double PropertyTax = 0.87;
}
else if(State == "PA")
{
double PropertyTax = 1.35;
}
else if(State == "RI")
{
double PropertyTax = 1.35;
}
else if(State == "SC")
{
double PropertyTax = 0.5;
}
else if(State == "D.C.")
{
double PropertyTax = 0.46;
}
else if(State == "SD")
{
double PropertyTax = 1.28;
}
else if(State == "TN")
{
double PropertyTax = 0.86;
}
else if(State == "TX")
{
double PropertyTax = 1.18;
}
else if(State == "UT")
{
double PropertyTax = 0.6;
}
else if(State == "VT")
{
double PropertyTax = 1.59;
}
else if(State == "WA")
{
double PropertyTax = 0.92;
}
else if(State == "WV")
{
double PropertyTax = 0.49;
}
else if(State == "WI")
{
double PropertyTax = 1.76;
}
else if(State == "WY")
{
double PropertyTax = 0.58;
}
String houseValue = JOptionPane.showInputDialog("Enter the value of the home");
double hValue = Integer.parseInt(houseValue);
double product = PropertyTax * hValue;
JOptionPane.showMessageDialog(null, "The property tax is " +product);
}
}
共有1个答案
赫连法
您可以用另一种方法执行此操作，并删除所有if/else语句。在输入框中显示状态列表，用户可以从中选择所需状态。选择的索引与包含每个状态的所有Tex速率的并行数组相关。有几种方法可以使这更容易。
// Component for JOptionPane to ensure it is always displayed on top
JFrame iFrame = new JFrame();
iFrame.setAlwaysOnTop(true);
iFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
iFrame.setLocationRelativeTo(null);
double propertyTax = 0.0d;
// Parallel Arrays
// List values t display in Input-Box
String[] states = {"Alabama", "Alaska", "Arizona", "Arkansas", "California",
"Colorado", "Connecticut", "Delaware", "Florida", "Georgia",
"Hawaii", "Idaho", "Illinois", "Indiana", "Iowa", "Kansas",
"Kentucky", "Louisiana", "Maine", "Maryland", "Massachusetts",
"Michigan", "Minnesota", "Mississippi", "Missouri", "Montana",
"Nebraska", "Nevada", "New Hampshire", "New Jersey", "New Mexico",
"New York", "North Carolina", "North Dakota", "Ohio", "Oklahoma",
"Oregon", "Pennsylvania", "Rhode Island", "South Carolina",
"South Dakota", "Tennessee", "Texas", "Utah", "Vermont", "Virginia",
"Washington", "West Virginia", "Wisconsin", "Wyoming"};
// Tax rates related to the above States
double[] taxes = {0.33d, 1.04d, 0.72d, 0.52d, 0.74d, 0.6d, 1.63d, 0.43d,
0.97d, 0.83d, 0.26d, 0.69d, 1.73d, 0.85d, 1.29d, 1.01d,
0.72d, 0.18, 1.04d, 1.09d, 0.87d, 1.05d, 1.05d, 0.52d,
0.91d, 0.83d, 1.76d, 0.84d, 1.86d, 1.89d, 0.55d, 1.23d,
0.78d, 1.42d, 1.36d, 0.74d, 0.87d, 1.35d, 1.35d, 0.5d,
0.46d, 1.28d, 0.86d, 1.18d, 0.6d, 1.59d, 0.92d, 0.49d,
1.76d, 0.58d};
// Show Input-Box dialog...
String selectedState = (String) JOptionPane.showInputDialog(iFrame, "Select a State:",
"State Selection", JOptionPane.QUESTION_MESSAGE, null, states, "");
iFrame.dispose();
if (selectedState != null && !selectedState.equals("")) {
// Get the index value of the selected State so as
// to get the tax rate related to that state.
for (int i = 0; i < states.length; i++) {
if (selectedState.equals(states[i])) {
propertyTax = taxes[i];
break;
}
}
// Get house value from User...
String houseValue = JOptionPane.showInputDialog(iFrame, "Enter the value of the home", "Home Value",
JOptionPane.QUESTION_MESSAGE);
if (houseValue == null || houseValue.equals("")) {
houseValue = "0.0";
}
iFrame.dispose();
double hValue = Double.parseDouble(houseValue);
// Calculate the property tax
double product = hValue * (propertyTax / 100.0d);
// Display results...
JOptionPane.showMessageDialog(iFrame, "The property tax is " + product);
iFrame.dispose();
}
不一定更短，但它确实消除了用户输入错误的可能性。
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