java - 为什么 getter 方法不返回任何对象的属性？

Question

我的程序应该返回两个不同对象的不同属性。在我的主要方法中，我在创建新对象时将这些属性设置为参数。但是当我调用这些 getter 方法(我在一个单独的类中编写的，如果需要的话我可以发布该类)时，它不会返回所有属性。它仅打印出第一个属性(也设置为第一个参数)，而不打印其他两个值。我不知道我哪里做错了。

我的代码:主类:

    package main;

public class Main {

    public static void main(String[] args) {

        //creating object for book 1 
        Book book1 = new Book("The brief history of time", "111", new String[]{"S. hawking", "hawking's friends"});
        //creating object for book 2
        Book book2 = new Book("100 years of solitude", "222", new String[]{"G.marquez", "marquez's friend"});

        System.out.println("All info for the first book: \n");

        System.out.println("Name: " + book1.getName());
        System.out.println("ISBN: " + book1.getIsbn());
        System.out.println("Authors: " + book1.getAuthors());

        System.out.println("\n\n");
        System.out.println("All info for the second book: \n");
        System.out.println("Name: " + book2.getName());
        System.out.println("ISBN: " + book2.getIsbn());
        System.out.println("Authors: " + book2.getAuthors());

    }

}

图书类别:

    package main;

public class Book {
    //variables

    private String name;
    private String isbn;
    private String[] authors;

    //constructors
    public Book(String name, String isbn, String[] authors) {
        this.name = name;
        this.isbn = name;
        this.authors = authors;

    }

    //setters
    public void setName(String name) {
        this.name = name;
    }

    public void setIsbn(String isbn) {
        this.isbn = isbn;
    }

    public void setAuthors(String[] authors) {
        this.authors = authors;
    }

    //getters
    public String getName() {
        return name;
    }

    public String getIsbn() {
        return isbn;
    }

    public String[] getAuthors() {
        return authors;
    }

}

Answer 1

您需要迭代authors数组才能打印其中的字符串。像这样的东西:

    System.out.println("All info for the first book: \n");

    System.out.println("Name: " + book1.getName());
    System.out.println("ISBN: " + book1.getIsbn());
    for (String author : book1.getAuthors()) {
        System.out.println("Author: " + author);
    }

您的 Book 类构造函数也存在问题:

public Book(String name, String isbn, String[] authors) {
    this.name = name;
    this.isbn = name; // this.isbn is not name!
    this.authors = authors;
}

必须是:

public Book(String name, String isbn, String[] authors) {
    this.name = name;
    this.isbn = isbn;
    this.authors = authors;
}