Java柠檬汁计算器

Question

任务是：

>

在输出屏幕顶部显示任何欢迎信息

创建变量来保存一杯柠檬水的价格。

显示每杯的价格。

询问用户的姓名，并将其存储为字符串对象。只要有可能，就用名字称呼用户。

询问用户他们想订购多少杯柠檬水。将其保存为具有适当数据类型的变量。

将8%的圣地亚哥税率作为常量变量存储在您的计划中。

计算小计、税金总额、总价，并显示在屏幕上。

询问用户想要如何支付柠檬水，并将输入保存为char变量。

要求用户输入“m”表示金钱，“c”表示信用卡，“g”表示黄金

使用DecimalFormat类，使打印到屏幕上的所有货币数据显示小数点后两位，以及一个“$”符号。

需要帮助了解如何在我的程序中将8%的税率作为常量变量，这样我就可以计算小计、总税和总价，并将其显示在屏幕上

到目前为止，这就是我所拥有的：

import java.util.Scanner;
import javax.swing.JOptionPane;
import java.text.DecimalFormat;

public class FirstProgram {

    public static void main(String[] args) {
        double cost = 7.55;
        double amount = 7.55;
        final double CA_SALES_TAX = 0.08; 
        int tax, subtotal, total;
        subtotal = (int) (amount * cost);
        tax = (int) (subtotal * CA_SALES_TAX);
        total = tax + subtotal;

        Scanner input = new Scanner(System.in);
        double fnum = 7.55, tax1 = fnum * 0.08, answer = tax1 + fnum; 
        System.out.println("Welcome to the best Lemonade you'll ever taste! ");

        System.out.println("My lemonade would only cost you a measly: $" + amount);

        System.out.println("What is your name?");

        String first_name;
        first_name = input.nextLine();

        System.out.println("Hi " +first_name+ ", how many glasses of lemonade would you like?");
        fnum = input.nextDouble();
        System.out.println("Subtotal: $" + (amount * fnum));

        System.out.println("Tax:    $" + (tax1 * CA_SALES_TAX));
        tax1 = input.nextDouble();

任何帮助都很感激

Answer 1

看起来您已经将增值税设置为常量，这就是“final”关键字的用途。至于你的代码，我看到了一些冗余，不确定你为什么要转换成整数。我做了一些MOD，我想是你想要的。

public static void main(String[] args) {
    double cost = 7.55;
    final double CA_SALES_TAX = 0.08;
    double subtotal,tax,total;

    Scanner input = new Scanner(System.in);
    System.out.println("Welcome to the best Lemonade you'll ever taste! ");
    System.out.println("My lemonade would only cost you a measly: $" + cost);

    System.out.println("What is your name?");
    String first_name = input.nextLine();

    System.out.println("Hi " +first_name+ ", how many glasses of lemonade would you like?");
    int fnum = input.nextInt();

    //calc subtotal, tax, total 
    subtotal = fnum * cost;
    tax = subtotal *CA_SALES_TAX; 
    total = tax + subtotal;

    // print them all out 
    System.out.println("Subtotal: $" + (subtotal));
    System.out.println("Tax: $" + (tax));
    System.out.println("Total Price: $" + (total));
}