Question

我正在制作一个程序，我差不多完成了它。我唯一想不通的是如何作为y或n的用户，然后在程序中显示布尔值为true或false。它一直给我一个错误。这是我正在使用的代码。我只是希望它在驱动程序中的最后一个print语句执行时显示true或false。谢谢

public class Customer extends Person {

protected int customerNum;
protected boolean mailingList;
protected char answ;

public Customer() {
    super();
    // TODO Auto-generated constructor stub
}

public Customer(String name, String address, double telephone,
        int customerNum, boolean mailingList) {
    super(name, address, telephone);
    this.customerNum = customerNum;
    this.mailingList = mailingList;
}

/**
 * @return the customerNum
 */
public int getCustomerNum() {
    return customerNum;
}

/**
 * @param customerNum the customerNum to set
 */
public void setCustomerNum(int customerNum) {
    this.customerNum = customerNum;
}

/**
 * @return the mailingList
 */
public boolean isMailingList() {
    return mailingList;
}

/**
 * @param mailingList the mailingList to set
 */
public void setMailingList(boolean mailingList) {
    try {
        if(answ == 'y'){
            mailingList = true;
        }
        else if(answ == 'n')
            mailingList = false;
        this.mailingList = mailingList;
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

/* (non-Javadoc)
 * @see java.lang.Object#toString()
 */
@Override
public String toString() {
    return "Customer [customerNum=" + customerNum + ", mailingList="
            + mailingList + "]";
}

然后是驱动程序

import java.util.Scanner;


public class CustomerDriver extends PreferredCustomer {

/**
 * @param args
 */
public static void main(String[] args) {



    Scanner kb = new Scanner(System.in);

    PreferredCustomer customer1 = new PreferredCustomer();

    System.out.println("Enter Customer Name: ");
    customer1.setName(kb.nextLine());

    System.out.println("Enter Customer Address: ");
    customer1.setAddress(kb.nextLine());

    System.out.println("Enter Telephone Number: ");
    customer1.setTelephone(kb.nextDouble());

    System.out.println("Enter the Customer Number: ");
    customer1.setCustomerNum(kb.nextInt());

    System.out.println("Does customer wish to be on mailing list? \n" + 
    "Enter 'y' for yes and 'n' for no: ");
    customer1.setMailingList(kb.nextBoolean());

    System.out.println("Enter amount of Customer's Purchase: ");
    customer1.setPurchases(kb.nextDouble());

    System.out.println("Customer's Discount is as follows: " + customer1.getDiscountLevel() + "\n");

    System.out.println("Customers Name: " + customer1.getName() + "\nCustomers Address: " + customer1.getAddress() + "\nCustomers Phone" +  customer1.getTelephone() + 
            "\nCustomer Number: " + customer1.getCustomerNum() + "\nMailing List Preferrence: " + customer1.isMailingList() + "\nCustomer's Purchase Amount " + 
            customer1.getPurchases() + "\nCustomers Discount Rate (if any) :" + customer1.getDiscountLevel());




    // TODO Auto-generated method stub

}

}

Answer 1

您只能在token is literally "true" or "false"时使用nextBoolean()。否则，它将抛出一个InputMismatchException。答案“y”和“n”不计算在内。你需要提示文字值“true”或“false”或者read the y/n response as a String并自己转换为布尔值，如：

String yOrN = kb.next();
if ("y".equals(yOrN)) customer1.setMailingList(true);

更新：我现在看到您的setMailingList()方法中已有“if answer =='y'”逻辑。但是，您尝试将布尔值传递给该方法，然后根据answ字段的值更改该布尔值，该字段永远不会赋值。在工作之前，您还需要处理代码的这一部分。我会说你将布尔值传递给该方法是正确的，所以“y或n”逻辑应该从它移出到你的main方法。

Answer 2

y和n无效Booleans。您需要输入true或false才能生效。

你最好的选择是做这样的事情：

if (kb.nextLine().equals("y")) {
    customer1.setMailingList(true);
} else {
    customer1.setMailingList(false);
}

Answer 3

您要求用户输入char输入'y'或'n'，但您的代码实际上是期望'true'或'false'

customer1.setMailingList（kb.nextBoolean（））;

你可能想要改变它以从用户那里获取字符串输入并检查

Answer 4

System.out.println("Does customer wish to be on mailing list? \n" + 
    "Enter 'y' for yes and 'n' for no: ");
    customer1.setMailingList(kb.nextBoolean());

在这里，您要求用户输入字符y或n。当你调用nextBoolean时，你正在请求一个布尔输入。 y或n都不是布尔值。 boolean是true或false。相反，提示用户输入true或false，而不是y或n。或明确指出y = true和n = false;

如何在方法和打印结果中正确使用布尔值

4 个答案: