Question

所以，我是面向对象编程的新手。我正在做下一个练习：

给定一个定义为具有以下属性的类Book：
```
Author author;
String title;
int noOfPages;
boolean fiction;
```
为每个属性编写标准get / set方法标题。
[编码]实际上根据练习1中所要求的属性和get / set方法编写和编译Book类。

这是我的代码：

public class Author {

    //private variable
    private String name;
    private String gender;  
    //constructor
    public Author (String name, String gender){
        this.name = name;
        this.gender = gender;   
    }
    //getters
    public String getName(){
        return name;  
    }
    public String getGender(){
        return gender;
    }
public class Book {

    //private variables
    private Author author;
    private String title;
    private int noOfPages;
    private boolean fiction;

    //constructor
    public Book(String title, int noOfPages, boolean fiction){
        this.author=new Author ("Jacquie Barker","Female");
        this.title = title;
        this.noOfPages=noOfPages;
        this.fiction = fiction;    
    }

    //getters
    public Author getAuthorsName(){
        return this.author;
    }
    public String getTitle(){
        return title;
    }

    public int getNoOfPages(){
        return noOfPages;
    }

    public boolean getFiction(){
        return fiction;
    }

    //setters
    public void setAuthor(Author newAuthor){
        author=newAuthor;
    }
    public void setTitle (String title){
        this.title=title;
    }
    public void setNoOfPages(int noOfpages){
        this.noOfPages=noOfpages;
    }
    public void setfiction(boolean fiction){
        this.fiction=false;
    }

    public String toString(){
        return "Title: " + this.title + "\n"+"Author: " + this.author + "\n" +
               "No. of pages: " + this.noOfPages + "\n" + "Fiction: " + this.fiction;
    }
}

以下是主要的摘录：

Title: Beginning in Java Objects

Author: book.Author@15db9742

No. of pages: 300

Fiction: true

如您所见，该程序不会打印作者的姓名。

我感谢所有人的帮助！

Answer 1

这里有两种选择。首先，您可以简单地重构Book.toString()方法中的代码以打印作者的实际名称：

public String toString(){
    return "Title: " + this.title + "\n"+"Author: " + this.author.getName() + "\n" +
           "No. of pages: " + this.noOfPages + "\n" + "Fiction: " + 
}

其次，您可以覆盖toString()类中的Author方法以返回作者的姓名。然后，您可以保留Book.toString()方法，因为当您尝试打印toString()对象时，Java会调用此Author方法：

public class Author {
    // print the author's name when an Author object appears in a print statement
    public String toString() {
       return this.name;
    }
}

然后和你一样：

public class Book {
    public String toString(){
        return "Title: " + this.title + "\n"+"Author: " + this.author + "\n" +
           "No. of pages: " + this.noOfPages + "\n" + "Fiction: " + this.fiction;
    }
}

Answer 2

您应该在Author类中实现toString。

    public class Author {

        //private variable
        private String name;
        private String gender;  
        //constructor
        public Author (String name, String gender){
            this.name = name;
            this.gender = gender;   
        }
        ...
        public String toString() {
          return "Name " + name + "\t Gender: " + gender + "\n"; //Somethign like this.
        } 
}

Answer 3

如果您使用的是Eclipse，IntelliJ或NetBeans等IDE，则可以让它们生成这些标准的getter和setter。浏览菜单。

这样就不存在拼写错误（如setfiction中所述，f应该是大写字母。）

由于您是初学者，您应该先自己编写，然后让它们自动生成，这样您就可以比较您的解决方案。

Answer 4

如果要返回作者姓名，请将其更改为：

public Author getAuthorsName(){
    return this.author;
}

到：

public String getAuthorsName(){
    return this.author.getName();
}

目前您正在从您的方法返回类Author的对象，因此要获取作者的姓名，您需要在调用代码中调用author.getName()或更改现有方法以返回作者的如上所述的名称。

从Book-class获取Author-name简单

4 个答案: