问题：

异常在线程"main"java.util.NoSuchElement异常错误和程序打印出错误的结果

诸葛乐逸

2023-03-14

我必须写一个程序来计算邮寄的东西的运费。

以下是一些规范以及练习运行应该是什么样子：

计算：

用法：发货方法成本隔夜$5*重量两天$2*重量经济$1*重量（是的，这只是=重量）数据验证在此程序中，您还需要在主方法中执行一些验证。明确地：

项目说明不能为空。物品重量必须为

运行#1：未输入项目说明：

输入项目描述：

运行#2：输入的项目重量无效：

输入项目说明：一个大框

运行#3:输入的装运方式无效：

输入物品描述：一个大盒子输入物品重量（磅）： 3.5

您希望以多快的速度发货：（O）vernight（T）两天（E）经济（可能需要7天）选择一个选项：P无效的发货方式。程序无法继续

运行#4：生成发票

输入物品描述：一个大盒子输入物品重量（磅）： 3.5

您希望以多快的速度发货包裹：（O）vernight（T）两天（E）经济（可能需要7天）选择一个选项：O

***我们装运发票***项目描述：一个大箱子项目重量：3.50装运方法：O总成本：$17.50

分解您必须使用下面提供的分解。为了最大限度地保持理智，请记住在开发模式下一次构建和测试一个方法。其中两个方法已经为您编写，并作为本练习的代码模板的一部分提供。

用法：double getWallHeight（扫描仪scnr）-此方法从主方法调用。它接受扫描仪作为参数，提示用户输入墙高度，并将用户输入的值返回给main方法。

使用：双getWallWidth（扫描仪scnr）-此方法是从main方法调用的。它接受扫描仪作为参数，提示用户墙壁高度，并将用户输入的值返回给main方法。

用法：double CalcWallRea（双墙高，双墙宽）-此方法从主方法调用。它接受墙高和墙宽，并以平方英尺为单位计算墙面积。

用法：double calcGallons（double wallArea）-此方法从主方法调用。它接受墙面积，并确定整个房间需要多少油漆。

用法：void displayResults（需要双wallArea、双gallonspaintResults）-此方法从主方法调用。它接受瓦莱拉和油漆房间所需的油漆量。它以整数形式向用户显示结果，包括行走区域和需要购买的油漆罐数量。

这是我的密码：

import java.util.*;
import java.util.Scanner; 

public class WeShipIt {

public static final int OVERNIGHT_CHARGE = 5;
public static final int TWO_DAY_CHARGE = 2;
public static final int ECONOMY_CHARGE = 1;

public static void main(String[] args){
  Scanner keyboard = new Scanner(System.in);  //scanner object to pass around
  double weight;
  String itemDescription;
  char shipMethod;
  double shippingCost;
    
  itemDescription = getitemDescription(keyboard);
  weight = getShipWeight(keyboard);
  shipMethod = getShipClass(keyboard);
  shippingCost = calculateShipping(shipMethod, weight);
  
  
  if (itemDescription.length() == 0){
     
     System.out.println("Invalid description. Program cannot continue");
     System.exit(0);
  } else {
     getShipWeight(keyboard);
     
     if (weight <= 0){
     
     System.out.println("Invalid shipping weight. Program cannot continue");

     } else {
     getShipClass(keyboard);
     
      if (!(shipMethod == 'O' || shipMethod == 'T' || shipMethod == 'E')){
     System.out.println("Invalid shipping method. Program cannot continue");
     
     } else {
     displayResults(itemDescription, weight, shipMethod, shippingCost);
     }
     }
     }
}
//get item description
  public static String getitemDescription(Scanner keyboard){
      
  System.out.println("Enter item description:");
  String itemDescription = keyboard.next();

  return itemDescription;
  }

//get item weight
public static double getShipWeight(Scanner console){
       
  System.out.println("Enter item weight in lbs:");
  double itemWeight = console.nextDouble();

  return itemWeight;
}

 //get user's choice for shipping method and return it
 public static char getShipClass(Scanner keyboard) {
  char shipMethod;

  //get shipping method
  System.out.println();
  System.out.println("How would you like to ship your package:");
  System.out.println("(O)vernight");
  System.out.println("(T)wo Days");
  System.out.println("(E)conomy (may take up to 7 days)");
  System.out.println("Choose an option: ");
  shipMethod = keyboard.next().charAt(0); //Prof. Dan says leave this line in here. Will explain in 
 class.
  shipMethod = Character.toUpperCase(shipMethod);
  
  return shipMethod;
}

 //calculate and return shipping charge
 public static double calculateShipping(char shipMethod, double weight){
  double shipCharge;
  
  if (shipMethod == 'O') {
  shipCharge = weight * OVERNIGHT_CHARGE;
  } 
  else if (shipMethod == 'T') {
  shipCharge = weight * TWO_DAY_CHARGE;
  } 
  else if (shipMethod == 'E') {
  shipCharge = weight * ECONOMY_CHARGE;
  } else {
  shipCharge = 0;
  }
  return shipCharge;
}

 //display shipping charge invoice
 public static void displayResults(String itemDescription, double shipWeight, char shipMethod, double 
 shipCost) {
  System.out.println();
  System.out.println("*** WE SHIP INVOICE ****");
  System.out.println("Item Description: " + itemDescription);
  System.out.printf("Item Weight: %.2f\n" + shipWeight);
  System.out.println("Ship Method: " + shipMethod);
  System.out.printf("Total Cost: $%.2f\n" + shipCost);
 }
}

这是我使用“box 3.5 0”作为输入时的输出：

输入项目说明：输入项目重量（磅）：

您希望如何运送包裹：（O）vernight（T）两天（E）经济（可能需要7天）选择一个选项：输入物品重量（磅）：

我不需要重新打印输入，但我很困惑为什么它再次要求项目的重量，而不打印出最终结果。

我也得到这个错误：

Exception in thread "main" java.util.NoSuchElementException
at java.base/java.util.Scanner.throwFor(Scanner.java:937)
at java.base/java.util.Scanner.next(Scanner.java:1594)
at java.base/java.util.Scanner.nextDouble(Scanner.java:2564)
at WeShipIt.getShipWeight(WeShipIt.java:67)
at WeShipIt.main(WeShipIt.java:35)

我已经试了几个小时来自己解决这个问题，但我请求帮助作为最后手段。我是计算机科学的新手，可能犯了一些愚蠢的错误。非常感谢。

共有3个答案

岳晟

2023-03-14

您显示的代码有2个错误：

1:System.out.printf（“项目重量：%.2f\n”装运重量）和
System.out.printf（“总成本：$%.2f\n”发货成本）执行此操作将引发MissingFormatArgumentException 原因当使用printf并声明参数时，它会使用在逗号之后传递给它的第一个变量（要打印的值）自我调整。在本例中，没有任何逗号，因此它不会识别并抛出MissingFormatArgumentException。

相反，你应该这样写：

System.out.printf("Item Weight: %.2f\n",shipWeight);
System.out.printf("Total Cost: $%.2f\n", shipCost);

2：您正在调用getShipWeight（键盘）和getShipClass（键盘）两次第一次，当用户刚进入程序时第二次，在else语句中<这迫使您再次输入重量和装运方式。

以下是最后的变化：

public static final int OVERNIGHT_CHARGE = 5;
    public static final int TWO_DAY_CHARGE = 2;
    public static final int ECONOMY_CHARGE = 1;

    public static void main(String[] args){
      Scanner keyboard = new Scanner(System.in);  //scanner object to pass around
      double weight;
      String itemDescription;
      char shipMethod;
      double shippingCost;
        
      itemDescription = getitemDescription(keyboard);
      weight = getShipWeight(keyboard);
      shipMethod = getShipClass(keyboard);
      shippingCost = calculateShipping(shipMethod, weight);
      
      
      if (itemDescription.length() == 0){
         
         System.out.println("Invalid description. Program cannot continue");
         System.exit(0);
      } else {
          // getShipWeight(keyboard); <-- this is forcing uset to enter weight again. 
         if (weight <= 0){
         
         System.out.println("Invalid shipping weight. Program cannot continue");

         } else {
           // getShipClass(keyboard); <--  this is forcing user to again give shipping method
          if (!(shipMethod == 'O' || shipMethod == 'T' || shipMethod == 'E')){
         System.out.println("Invalid shipping method. Program cannot continue");
         
         } else {
         displayResults(itemDescription, weight, shipMethod, shippingCost);
         }
         }
         }
    }
    //get item description
      public static String getitemDescription(Scanner keyboard){
          
      System.out.println("Enter item description:");
      String itemDescription = keyboard.next();

      return itemDescription;
      }

    //get item weight
    public static double getShipWeight(Scanner console){
           
      System.out.println("Enter item weight in lbs:");
      double itemWeight = console.nextDouble();

      return itemWeight;
    }

     //get user's choice for shipping method and return it
     public static char getShipClass(Scanner keyboard) {
      char shipMethod;

      //get shipping method
      System.out.println();
      System.out.println("How would you like to ship your package:");
      System.out.println("(O)vernight");
      System.out.println("(T)wo Days");
      System.out.println("(E)conomy (may take up to 7 days)");
      System.out.println("Choose an option: ");
      shipMethod = keyboard.next().charAt(0); //Prof. Dan says leave this line in here. Will explain in 
      shipMethod = Character.toUpperCase(shipMethod);
      
      return shipMethod;
    }

     //calculate and return shipping charge
     public static double calculateShipping(char shipMethod, double weight){
      double shipCharge;
      
      if (shipMethod == 'O') {
      shipCharge = weight * OVERNIGHT_CHARGE;
      } 
      else if (shipMethod == 'T') {
      shipCharge = weight * TWO_DAY_CHARGE;
      } 
      else if (shipMethod == 'E') {
      shipCharge = weight * ECONOMY_CHARGE;
      } else {
      shipCharge = 0;
      }
      return shipCharge;
    }

     //display shipping charge invoice
     public static void displayResults(String itemDescription, double shipWeight, char shipMethod, double 
     shipCost) {
      System.out.println();
      System.out.println("*** WE SHIP INVOICE ****");
      System.out.println("Item Description: " + itemDescription);
      System.out.printf("Item Weight: %.2f\n",shipWeight); // <-- changed
      System.out.println("Ship Method: " + shipMethod);
      System.out.printf("Total Cost: $%.2f\n", shipCost);  // <-- changed
     }

输出：

Enter item description:
box
Enter item weight in lbs:
3.5

How would you like to ship your package:
(O)vernight
(T)wo Days
(E)conomy (may take up to 7 days)
Choose an option: 
O

*** WE SHIP INVOICE ****
Item Description: box
Item Weight: 3.50
Ship Method: O
Total Cost: $17.50

曹兴贤

2023-03-14

很好，你正在学习java。

我们的计划需要做一点小小的改变<代码>获取装运重量

请使用此代码

import java.util.Scanner;

public class WeShipIt {

    public static final int OVERNIGHT_CHARGE = 5;
    public static final int TWO_DAY_CHARGE = 2;
    public static final int ECONOMY_CHARGE = 1;

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in); // scanner object to pass around
        double weight;
        String itemDescription;
        char shipMethod;
        double shippingCost;

        itemDescription = getitemDescription(keyboard);
        /*weight = getShipWeight(keyboard);
        shipMethod = getShipClass(keyboard);
        shippingCost = calculateShipping(shipMethod, weight);*/

        if (itemDescription.length() == 0) {

            System.out.println("Invalid description. Program cannot continue");
            System.exit(0);
        } else {
            weight = getShipWeight(keyboard);

            if (weight <= 0) {

                System.out.println("Invalid shipping weight. Program cannot continue");

            } else {
                shipMethod =getShipClass(keyboard);
                shippingCost = calculateShipping(shipMethod, weight);

                if (!(shipMethod == 'O' || shipMethod == 'T' || shipMethod == 'E')) {
                    System.out.println("Invalid shipping method. Program cannot continue");

                } else {
                    displayResults(itemDescription, weight, shipMethod, shippingCost);
                }
            }
        }
    }

//get item description
    public static String getitemDescription(Scanner keyboard) {

        System.out.println("Enter item description:");
        String itemDescription = keyboard.next();

        return itemDescription;
    }

//get item weight
    public static double getShipWeight(Scanner console) {

        System.out.println("Enter item weight in lbs:");
        double itemWeight = console.nextDouble();
        return itemWeight;
    }

    // get user's choice for shipping method and return it
    public static char getShipClass(Scanner keyboard) {
        char shipMethod;

        // get shipping method
        System.out.println();
        System.out.println("How would you like to ship your package:");
        System.out.println("(O)vernight");
        System.out.println("(T)wo Days");
        System.out.println("(E)conomy (may take up to 7 days)");
        System.out.println("Choose an option: ");
        shipMethod = keyboard.next().charAt(0); // Prof. Dan says leave this line in here. Will explain in class.
        shipMethod = Character.toUpperCase(shipMethod);

        return shipMethod;
    }

    // calculate and return shipping charge
    public static double calculateShipping(char shipMethod, double weight) {
        double shipCharge;

        if (shipMethod == 'O') {
            shipCharge = weight * OVERNIGHT_CHARGE;
        } else if (shipMethod == 'T') {
            shipCharge = weight * TWO_DAY_CHARGE;
        } else if (shipMethod == 'E') {
            shipCharge = weight * ECONOMY_CHARGE;
        } else {
            shipCharge = 0;
        }
        return shipCharge;
    }

    // display shipping charge invoice
    public static void displayResults(String itemDescription, double shipWeight, char shipMethod, double shipCost) {
        System.out.println();
        System.out.println("*** WE SHIP INVOICE ****");
        System.out.println("Item Description: " + itemDescription);
        System.out.println("Item Weight: "+ shipWeight);
        System.out.println("Ship Method: " + shipMethod);
        System.out.println("Total Cost: $"+ shipCost);
    }
}

冯元魁

2023-03-14

实际上，您已经在else块中调用了“getShipWeight（键盘）”和“getShipClass（键盘）”，这就是它再次请求权重的原因。只要对这些语句进行注释，代码就会正常运行。

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异常在线程"main"java.util.NoSuchElement异常错误和程序打印出错误的结果

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