java - 私有(private)字符串方法错误，获取正确用户输入的问题

Question

我在编写 Java 程序时遇到困难，特别是在使用 EnterCustomerName 方法时。我使用了字符串，以便我可以从用户那里获取文字输入。还有其他错误，但这个我不明白。我是 Java 编程新手，因此非常感谢任何帮助。

这是一个针对水果和蔬菜商店的程序。

import java.util.Scanner;


public class FruitVegShop

{


    private void printWelcomeMessage()
    { // print the welcome message
    System.out.println("Welcome to Rocky Fruit and Vegetable Market");
    }


    private String enterCustomerName()
    { // prompt for, read and return a customer name
        Scanner in = new Scanner (System.in);
        System.out.println("Please enter the customer's name: ");
        String customerName;
        customerName = in.nextLine();
        System.out.printf("Hello %s\n", customerName);
        return "";
    }


    private String enterProduceName()
    { // prompt for, read and return the name of the produce
        Scanner in = new Scanner(System.in);
        System.out.println("Please enter the name of the produce");
        String name;
        name = in.nextLine();
        System.out.printf("P: %s\n", name);
        return "";
    }


    private void printPurchaseNumber(int purchaseNumber)
    { // print the number of the purchase

    }


    private double enterProduceWeight(String name)
    { // prompt for, read and return the weight of the produce
        Scanner in = new Scanner (System.in);
        System.out.println("Please enter the weight of the produce: ");
        double weight;
        weight = in.nextDouble();
        System.out.printf("Produce Weight: %d\n", weight);
        return 0;
    }


    private double enterProduceCost(String name)
    { // prompt for, read and return the cost of the produce
        Scanner in = new Scanner (System.in);
        System.out.println("Please enter the price of the produce: ");
        double costPerKg;
        costPerKg = in.nextDouble();
        System.out.printf("Produce Price: $%d\n", costPerKg);
        return 0;
    }


    private void printPurchase(String name, double weight, double costPerKg, double cost)
    { // print the details of one pruchase

    double produceTotal;

    System.out.println("Produce:");
    System.out.printf("Produce: %d\n", name);
    System.out.printf("Weight (kg): %d\n", weight);
    System.out.printf("@ $%d.2\n /kg", costPerKg);
    System.out.printf("TOTAL: $%d.2\n", produceTotal); // ERROR: variable produceTotal might not have been initialized

    produceTotal = weight * costPerKg;

    }


    private boolean discount(String name)
    { // determine if the customer is eligle for a discount and return true or false
        if(


        return scannerObject.nextLine().equalsIgnoreCase(“y”);
    }


    private void printTotalCost(String name, int numberOfPurchases, double cost, boolean discount)
    { // print the total cost of the order and discount information if neccessary
    }


    private void printExitMessage(String name)
    { // print the exit message
    }


    private void processCustomer()
    { // process one customer's order
        String customerName,        // the name of the customer
                produceName;        // the name of the produce

        double produceWeight,       // the weight ofthe produce
                produceCostPerKg,   // the cost per kilo of the produce
                purchaseCost,       // the cost of the purchase
                totalCost = 0;      // the total cost of the order

        int purchaseNumber = 0;     // the number of the current purchase

        boolean discount;           // boolean to say if customer is eligible for a discount

        printWelcomeMessage();      // print the title message

        customerName = enterCustomerName(); // get the customer name

        purchaseNumber++;                                   // increment the number of the purchase
        printPurchaseNumber(purchaseNumber);                // print the number of the purchase
        produceName = enterProduceName();                   // get the name of the produce item
        produceWeight = enterProduceWeight(produceName);    // get the weight of the purchase
        produceCostPerKg = enterProduceCost(produceName);   // get the cost per kg

        purchaseCost = produceWeight * produceCostPerKg;    // calculate the cost of the purchase
        totalCost += purchaseCost;                          // add to total cost

        printPurchase(produceName, produceWeight, produceCostPerKg, purchaseCost); // print the purchase details

        discount = discount(customerName);  // determine if the customer is eligible for a discount

        printTotalCost(customerName, purchaseNumber, totalCost, discount); // print the total cost

        printExitMessage(customerName); // print the final exit message
    }


    public static void main(String [] args)
    {
        FruitVegShop fruitVegShop = new FruitVegShop();

        fruitVegShop.processCustomer();
    }
}

这是我得到的错误:

Welcome to Rocky Fruit and Vegetable Market
Please enter the customer's name:
Anonymous
Exception in thread "main" java.util.InputMismatchException
        at java.util.Scanner.throwFor(Scanner.java:864)
        at java.util.Scanner.next(Scanner.java:1485)
        at java.util.Scanner.nextInt(Scanner.java:2117)
        at java.util.Scanner.nextInt(Scanner.java:2076)
        at FruitVegShop.enterCustomerName(FruitVegShop.java:20)
        at FruitVegShop.processCustomer(FruitVegShop.java:102)
        at FruitVegShop.main(FruitVegShop.java:127)
Press any key to continue . . .

import java.util.Scanner;


public class FruitVegShop

{


	private void printWelcomeMessage()
	{ // print the welcome message
	System.out.println("                Welcome to Rocky Fruit and Vegetable Market");
	}


	private String enterCustomerName()
	{ // prompt for, read and return a customer name
		Scanner in = new Scanner (System.in);
		System.out.println("Enter the name of the customer ==> ");
		String customerName;
		customerName = in.nextLine();
	    return customerName;
	}


	private String enterProduceName()
	{ // prompt for, read and return the name of the produce
		Scanner in = new Scanner(System.in);
		System.out.println("Enter the name of the produce ==> ");
		String produceName;
		produceName = in.nextLine();
		return produceName;
	}


	private void printPurchaseNumber(int purchaseNumber)
	{ // print the number of the purchase
		int counter = 0;
		while ( counter <= 3 ) // loop the order 3 times
	
	}


	private double enterProduceWeight(String name)
	{ // prompt for, read and return the weight of the produce
		Scanner in = new Scanner (System.in);
		System.out.printf("Enter the weight (kg) of the %s\n ==> ", produceName);
		double produceWeight;
		produceWeight = in.nextDouble();
		return produceWeight;
	}


	private double enterProduceCost(String name)
	{ // prompt for, read and return the cost of the produce
		Scanner in = new Scanner (System.in);
		System.out.printf("Enter the cost per kg of the %s\n ==> ", produceName);
		double produceCostPerKg;
		produceCostPerKg = in.nextDouble();
		return produceCostPerKg;
	}


	private void printPurchase(String produceName, double produceWeight, double produceCostPerKg, double cost)
	{ // print the details of one pruchase

	double produceCost;

	System.out.println("--------------------------------------------------");
	System.out.printf("%f\n of %s\n at $%.2f\n per kg is $%.2f\n", produceWeight, produceName, produceCostPerKg, produceCost);
	System.out.println("--------------------------------------------------");

	produceCost = produceWeight * produceCostPerKg;

	}


	private boolean discount(String name)
	{ // determine if the customer is eligle for a discount and return true or false
		Scanner in = new Scanner(System.in);
		if (in.nextLine().equalsIgnoreCase("y"))
			return true;
		else
            return false;
	}


	private void printTotalCost(String name, int numberOfPurchases, double cost, boolean discount)
	{ // print the total cost of the order and discount information if neccessary

		double totalCost;
		double discountValue;

		System.out.println("**********************************************************************");
		System.out.printf("%s\n the total for %d\n fruit and vegetable purchases is $%.2f\n", customerName, purchaseNumber, totalCost);
		System.out.printf("This includes a discount of $%.2d\n", discountValue);
		System.out.println("**********************************************************************");

		// make a addition counter for the order.
		// set a discount value
	}


	private void printExitMessage(String name)
	{ // print the exit message
		System.out.printf("Thank you %s\n for shopping at the Rocky Fruit and Vegetable Market", customerName);
		System.out.println("Written by s0270780");
	}


	private void processCustomer()
	{ // process one customer's order
		String customerName,		// the name of the customer
				produceName;		// the name of the produce

		double produceWeight,		// the weight of the produce
				produceCostPerKg,	// the cost per kilo of the produce
				purchaseCost,		// the cost of the purchase
				totalCost = 0;		// the total cost of the order

		int purchaseNumber = 0;		// the number of the current purchase

		boolean discount;			// boolean to say if customer is eligible for a discount

		printWelcomeMessage();		// print the title message

		customerName = enterCustomerName(); // get the customer name

		purchaseNumber++;									// increment the number of the purchase
		printPurchaseNumber(purchaseNumber);				// print the number of the purchase
		produceName = enterProduceName();					// get the name of the produce item
		produceWeight = enterProduceWeight(produceName);	// get the weight of the purchase
		produceCostPerKg = enterProduceCost(produceName);	// get the cost per kg

		purchaseCost = produceWeight * produceCostPerKg;	// calculate the cost of the purchase
		totalCost += purchaseCost;							// add to total cost

		printPurchase(produceName, produceWeight, produceCostPerKg, purchaseCost); // print the purchase details

		discount = discount(customerName);	// determine if the customer is eligible for a discount

		printTotalCost(customerName, purchaseNumber, totalCost, discount); // print the total cost

		printExitMessage(customerName);	// print the final exit message
	}


	public static void main(String [] args)
	{
		FruitVegShop fruitVegShop = new FruitVegShop();

		fruitVegShop.processCustomer();
	}
}

C:\Users\Jockman\Desktop\The Fruit & Veg Shop\FruitVegShop.java:45: error: cannot find symbol
		System.out.printf("Enter the weight (kg) of the %f\n ==> ", produceName);
		                                                            ^
  symbol:   variable produceName
  location: class FruitVegShop
C:\Users\Jockman\Desktop\The Fruit & Veg Shop\FruitVegShop.java:55: error: cannot find symbol
		System.out.printf("Enter the cost per kg of the %s\n ==> ", produceName);
		                                                            ^
  symbol:   variable produceName
  location: class FruitVegShop
C:\Users\Jockman\Desktop\The Fruit & Veg Shop\FruitVegShop.java:93: error: cannot find symbol
		System.out.printf("%s\n the total for %d\n fruit and vegetable purchases is $%.2f\n", customerName, purchaseNumber, totalCost);
		                                                                                      ^
  symbol:   variable customerName
  location: class FruitVegShop
C:\Users\Jockman\Desktop\The Fruit & Veg Shop\FruitVegShop.java:93: error: cannot find symbol
		System.out.printf("%s\n the total for %d\n fruit and vegetable purchases is $%.2f\n", customerName, purchaseNumber, totalCost);
		                                                                                                    ^
  symbol:   variable purchaseNumber
  location: class FruitVegShop
C:\Users\Jockman\Desktop\The Fruit & Veg Shop\FruitVegShop.java:104: error: cannot find symbol
		System.out.printf("Thank you %s\n for shopping at the Rocky Fruit and Vegetable Market", customerName);
		                                                                                         ^
  symbol:   variable customerName
  location: class FruitVegShop
5 errors

Tool completed with exit code 1

Answer 1

我认为您打算在 enterCustomerName() 和 enterProduceName() 中返回 name 而不是 "" > 改变

return "";

至

return customerName;

和

return name;

分别。此外，enterProduceWeight 和 enterProduceCost 不应 return 0;，但应 return Weight; 和 return costPerKg; (如果您希望它们在 printPurchase 中打印为非空且不是 0)。