java - 餐厅账单，初始化错误

Question

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

public class RestaurantBill3
{
   public static void main(String [] args)
   {
      //Constant
      final double TAX_RATE = 0.0675;      
      final double TIP_PERCENT = 0.15;

      //Variables                             
      double cost;  
      double taxAmount = TAX_RATE * cost;              //Tax amount 
      double totalWTax = taxAmount + cost;             //Total with tax
      double tipAmount = TIP_PERCENT * totalWTax;            //Tip amount
      double totalCost = taxAmount + tipAmount + totalWTax;  //Total cost of meal

      Scanner keyboard = new Scanner(System.in);

      System.out.print("What is the cost of your meal? ");
      cost = keyboard.nextDouble();

      System.out.println("Your meal cost $" +cost);

      System.out.println("Your Tax is $" + taxAmount);

      System.out.println("Your Tip is $" + tipAmount);

      System.out.println("The total cost of your meal is $" + totalCost);

      System.exit(0);                                        //End program
   }
}  

/*我不断收到错误消息，指出成本显然尚未初始化，但如果它正在等待输入，那么应该如何执行此操作？*/

Answer 1

您在这里指的是初始化之前的cost值:

double taxAmount = TAX_RATE * cost; 
double totalWTax = taxAmount + cost;       

将这些变量的初始化移到cost的初始化之后，这样cost在被引用时就会有一个值。