2 线程“main”中的方法异常 java.util.NoSuchElementException

Question

我不断收到 Exception in thread "main" java.util.NoSuchElementException 错误消息。我已经尝试过更换东西，但我仍然遇到这个问题

我尝试过用不同的方法声明变量，但似乎没有任何效果。

import java.util.Scanner;

public class LabProgram {

    public static double drivingCost(double drivenMiles, double milesPerGallon, double dollarsPerGallon) {

        double totalCost = (drivenMiles / milesPerGallon) * dollarsPerGallon;

        return totalCost;

    }

    public static void main(String[] args) {

        double milesG;

        double dollarsG;

        Scanner scnr = new Scanner(System.in);

        milesG = scnr.nextDouble();

        dollarsG = scnr.nextDouble();

        drivingCost(10.0, milesG, dollarsG);

        milesG = scnr.nextDouble();

        dollarsG = scnr.nextDouble();

        drivingCost(50.0, milesG, dollarsG);

        milesG = scnr.nextDouble();

        dollarsG = scnr.nextDouble();

        drivingCost(400.0, milesG, dollarsG);

    }

}

问题是：

使用输入参数drivenMiles、milesPerGallon 和dollarsPerGallon 编写一个driveCost() 方法，该方法返回驾驶这些里程的美元成本。所有项目都是 double 类型。如果使用 50 20.0 3.1599 调用该方法，则该方法返回 7.89975。

在程序中定义该方法，其输入是汽车的英里/加仑和汽油美元/加仑（均为双倍）。通过调用 DrivingCost() 方法 3 次，输出 10 英里、50 英里和 400 英里的汽油成本。输出每个浮点值，小数点后两位。

输入为：20.0 3.1599

预期产量：1.58 7.90 63.20

Answer 1

import java.util.Scanner;public class LabProgram {      /* Define your method here */   public static double drivingCost(double drivenMiles, double milesPerGallon, double dollarsPerGallon) {      double totalCost = (dollarsPerGallon * drivenMiles / milesPerGallon);      return totalCost;}      public static void main(String[] args) {      /* Type your code here. */      Scanner scnr = new Scanner(System.in);      double milesPerGallon = scnr.nextDouble();      double dollarsPerGallon = scnr.nextDouble();      double drivenMiles = 1;      System.out.printf("%.2f ", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 10);      System.out.printf("%.2f ", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 50);      System.out.printf("%.2f\n", drivingCost(drivenMiles, milesPerGallon, dollarsPerGallon) * 400);   }}

Answer 2

driveMiles 除以每加仑英里数，然后乘以每加仑美元，即可得出每英里行驶的汽油价格。注意：在这种情况下，drivenMiles 只需要传递给 movingCost。这就是为什么要添加整数 10、50 和 400 来调用。由于 DrivingCost 按此顺序具有milesPerGallon、dollarsPerGallon 和drivenMiles 参数，因此您必须使用相同的参数顺序调用该方法。“%.2f”将得到右边两位小数。添加 \n 后将另起一行。import java.util.Scanner;public class LabProgram {      public static double drivingCost(double milesPerGallon, double dollarsPerGallon, double drivenMiles) {      // calcuating the cost of gas      double totalCost = (drivenMiles / milesPerGallon) * dollarsPerGallon;      return totalCost;       }      public static void main(String[] args) {      Scanner scnr = new Scanner(System.in);      double milesPerGallon;      double dollarsPerGallon;      milesPerGallon = scnr.nextDouble();      dollarsPerGallon = scnr.nextDouble();      // order of the call to the method is important, printing cost of gas for 10, 50, and 400 miles      System.out.printf("%.2f ",drivingCost(milesPerGallon, dollarsPerGallon, 10));      System.out.printf("%.2f ",drivingCost(milesPerGallon, dollarsPerGallon, 50));      System.out.printf("%.2f\n",drivingCost(milesPerGallon, dollarsPerGallon, 400));   }}

Answer 3

import java.util.Scanner;public class LabProgram {   public static double drivingCost(double milesPerGallon, double dollarsPerGallon, double drivenMiles) {  return (drivenMiles / milesPerGallon) * dollarsPerGallon;}public static void main(String[] args) {  Scanner input = new Scanner(System.in);  double milesPerGallon, dollarsPerGallon;    milesPerGallon = input.nextDouble();  dollarsPerGallon = input.nextDouble();    System.out.printf("%.2f ", drivingCost(milesPerGallon, dollarsPerGallon, 10));  System.out.printf("%.2f ", drivingCost(milesPerGallon, dollarsPerGallon, 50));  System.out.printf("%.2f\n", drivingCost(milesPerGallon, dollarsPerGallon, 400));      }}

Answer 4

您在主函数中调用了scnr.nextDouble();六次。确保在运行程序时提供六个double类型的参数。目前，您传递的参数少于六个，并且scnr.nextDouble();抛出异常，因为它找不到下一个 double 类型的参数。