Question

我想说感谢您审核我的帖子以及我遇到的任何问题。我是java的新手所以我想知道你们是否可以帮我调试这个程序。

import java.util.Scanner;

public class DebugExercise {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String area, inStr;
        int pages;

        System.out.println("Please enter your city");
        area = input.nextLine();

        System.out.println("Please enter page number " + area + "'s phone book");
        pages = input.nextInt();

        PhoneBook phoneBook = new PhoneBook(area, pages);
        phoneBook.display();
    }
}

class PhoneBook extends Book {

    private String area;
    private String size;

    PhoneBook(int pages, String city) {
        super();
        area = city;
        if (pages > 300) {
            size = "big";
        } else {
            size = "small";
        }
    }

    public display() {
        System.out.println( area + pages + size);
    }
}

class Book {

    protected int pages;

    public Book(int pages) {
        pages = pages;
    }

    public int getPages() {
        return pages;
    }
}

Answer 1

将参数交换到电话簿构造函数

public static void main(String[] args) {
            Scanner input = new Scanner(System.in);
            String area, inStr;  //there is no need of inStr as you are not using it so remove it if not used
            int pages;

            System.out.println("Please enter your city");
            area = input.nextLine();

            System.out.println("Please enter page number " + area + "'s phone book");
            pages = input.nextInt();

            PhoneBook phoneBook = new PhoneBook(pages,area); //swapp the argurments
              phoneBook.display(pages, area); //add arguments to this otherwise it will just show 0 
        }

在你的电话簿课程中添加参数到super

    PhoneBook(int pages, String city) {
        super(pages);  // u can even remove this its not needed
        area = city;
        if (pages > 300) {
            size = "big";
        } else {
            size = "small";
        }

public void display(int pages,String area) {
    System.out.println( area + pages + size);
}
}

现在它会起作用

Answer 2

首先，您有一些基本问题：

在您的Phonebook班级的构造函数PhoneBook(int pages, String city)中，您调用了super()，但是没有类Book的空构造函数，因此您必须调用super(pages)。
在Book类的构造函数中，您正在为pages变量分配它自己的值。你可能想要做的是this.pages = pages;。通过使用this.pages，您告诉java您指的是您正在创建的对象的字段pages，而不是指向传递给构造函数的参数。您可以在Oracle的文档here

this

java编程练习调试程序

2 个答案: