java - Java在子类中创建对象

在Book类中创建author对象时遇到了麻烦。这确实是Homework，我自己想出了所有方法，并且一直盯着这项作业两个小时。任何提示提示将不胜感激。我相信我只允许这个带有3个参数的Author构造函数，否则我将成为一个没有参数的Author构造函数，问题将会消失。

public class Author {

    protected String name;
    protected String email;
    protected char gender;

    public Author(String name, String email, char gender)
    {
        this.name = name;
        this.email = email;
        this.gender = gender;
    }

    public String getName()
    {
        return name;
    }

    public String getEmail()
    {
        return email;
    }

    public void setEmail(String email)
    {
        this.email = email;
    }

    public char getGener()
    {
        return gender;
    }

    public String toString()
    {
        return ( name + "(" + gender + ")@" + email);
    }


}

public class Book extends Author{

    private String name;
    private Author author;
    private double price;
    private int qtyInStock = 0;

    public Book(String name, Author author,Double price)
    {
        this.author = new author;
        this.name = name;
        this.price = price;

    }

    public Book(String name, Author author, double price, int qtyInStock)
    {

        this.name = name;
        this.author = author;
        this.price = price;
        this.qtyInStock = qtyInStock;
    }

    public String getName()
    {
        return name;
    }

    public Author getAuthor()
    {
        return author;
    }

    public double getPrice()
    {
        return price;
    }

    public void setPrice(double price)
    {
        this.price = price;
    }

    public int getQtyInStock()
    {
        return qtyInStock;
    }

    public void setQtyInStock(int qtyInStock)
    {
        this.qtyInStock = qtyInStock;
    }

    public String toString()
    {
        return (name + " by " + author + "(" + super.gender + ")at" + super.email);
    }
}

最佳答案

Book extends Author似乎很奇怪。 Book不是Author。

我认为您想做的是创建一个具有Book的Author对象，但是您已经将Author传递给您的Book构造函数，那是什么问题呢？

class Book {
    public Book(String title, Author author) {
        this.title = title;
        this.author = author;
    }
}

如果您想知道如何创建Author，请先创建它，然后再将其传递给Book。

Author author = new Author("bob", "[email protected]", 'm');
Book book = new Book("some title", author);

那有意义吗？

关于java - Java在子类中创建对象，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/35860475/