如何将对象数组从一种方法带到另一种方法并返回一个新对象

Question

我需要使用我的主方法中的数组并将其传输到我的 getBook 方法，然后将新创建的对象返回到主方法中的数组。

我决定将数组转移到下一个方法，方法是与扫描程序相同的方式进行操作，直到我需要在错误时调用该方法。

public class BookShopApplication 
{
    public static void main(String[] args) 
    {
        Scanner kybd = new Scanner (System.in);
        Book [] books = new Book [10];
        for (int i = 0; i > books.length; i++) 
        {
            books[i] = getBook(kybd, Book books[])
        }
    }
    public static Book[] getBook(Scanner kybd, Book books[]) 
    {

        System.out.println("What is the title of the next book?");
        String readTitle = kybd.nextLine();
        System.out.println("What is thr title of thje next book?");
        String readAuthor = kybd.nextLine();
        if (readAuthor == null)
        {
            for (int i = 0; i < books.length; i++)
            {
                books[i] = new Book();
                books[i].Book(readTitle);
            }
        }
        else 
        {
             for (int i = 0; i < books.length; i++)
            {
                books[i] = new Book();
                books[i].Book(readAuthor, readTitle);

            }
        }
    return books;
    }
}

我需要的结果是将书籍返回到数组并存储。

Answer 1

假设你的Book类看起来有点类似于这样：

class Book
{
    private String title;
    private String author;
    public void setTitle(String title)
    {
        this.title = title;
    }
    public void setAuthor(String author)
    {
        this.author = author;
    }
}

尝试单独实例化书籍并将它们存储在Book对象数组中更有意义。

public static void main(String[] args) {
    Scanner kybd = new Scanner (System.in);
    Book [] books = new Book [10];
    // < is needed not >
    for (int i = 0; i < books.length; i++) 
    {
        // book[] is empty, it has an index of 10 with no nodes
        // You need to create the instance to pass into the method
        books[i] = getBook(kybd, new Book());
    }
}
// This should only take the book it is working with
public static Book getBook(Scanner kybd, Book book)
{
    System.out.println("What is the title of the next book?");
    String readTitle = kybd.nextLine();
    System.out.println("What is the title of the next book?");
    String readAuthor = kybd.nextLine();
    if (!readAuthor.isEmpty())
    {
        book.setTitle(readTitle);
    }
    if(!readTitle.isEmpty())
    {
        book.setAuthor(readAuthor);
    }
    return book;
}

你也有很多语法错误 - 使用 .isEmpty() 方法而不是使用 === null .

更新：您从未在循环中实际创建Book实例。另外，for (int i = 0; i > books.length; i++) - 它应该是<而不是>.

此代码现在应该可以工作了。

Answer 2

好吧，你确实有一些语法错误：

首先，在你的 for 循环中，books[i] = getBook(kybd, Book books[])应该替换为 books[i] = getBook(kybd, books)(要将变量作为参数传递给方法，只需使用它的名称！

其次，在方法签名中，将public static Book[] getBook(Scanner kybd, Book books[])替换为public static Book[] getBook(Scanner kybd, Book[] books)(注意，它是Book[] books，而不是Book books[](。

希望这有帮助！

另外，正如 Jaquarh 评论的那样，您缺少一个分号！

编辑：此外，正如Jaquarh指出的那样，您的方法getBooks应该返回一本书，而不是数组。否则，该行 books[i] = getBook(kybd, Book books[])会崩溃。

Answer 3

for (int i = 0; i > books.length; i++) 
    {
        books[i] = getBook(kybd,books);
    }

应该做这个技巧，不会导致错误

这也是无效的：

  for (int i = 0; i < books.length; i++)
        {
            books[i] = new Book();
            **books[i].Book(readTitle);**
        }
    }
    else 
    {
         for (int i = 0; i < books.length; i++)
        {
            books[i] = new Book();
            **books[i].Book(readAuthor, readTitle);**

编辑