java - 面向对象编程的问题，创建多个实例

Question

我是 OOP 和 Java 类的新手，所以请耐心等待。

我正在尝试创建一个类，允许我存储有关书籍的数据，特别是字段:标题、作者、出版年份、页数、流派

然后，在该类中，我希望有一个运行的主程序，要求输入许多书籍，然后允许用户输入每本书的信息。然后，打印每本书的摘要。

我尝试编写一个类“bookClass”，允许输入书籍信息，然后编写一个类“bookTest”，使用 bookClass 创建一个数组。

这是本书的类:

public class bookClass {
    private String title;
    private String author;
    private String year;
    private String pageCount;
    private String genre;
    private static int bookCount;

    public bookClass(String title, String author, String year, String pageCount, String genre) {
        this.setTitle(title);
        this.setAuthor(author);
        this.setYear(year);
        this.setPageCount(pageCount);
        this.setGenre(genre);
        bookCount++;
    }

    public void setTitle(String title) {
        this.title = title;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
    public void setYear(String year) {
        this.year = year;
    }
    public void setPageCount(String pageCount) {
        this.pageCount = pageCount;
    }
    public void setGenre(String genre) {
        this.genre = genre;
    }

    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }

    public String getYear() {
        return year;
    }

    public String getPageCount() {
        return pageCount;
    }

    public String getGenre() {
        return genre;
    }

    public int getBookCount() {
        return bookCount
    }
}

这是主类:

import java.util.*;

public class bookTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.print("How many books would you like to enter: ");
        int bookAmount = input.nextInt(); input.nextLine();
        String[][] books2DArray = new String[bookAmount][5];
        for (String[] books1DArray: books2DArray) {
            System.out.print("Please enter the title: ");
            String title = input.nextLine();
            System.out.print("Please enter the author ");
            String author = input.nextLine();
            System.out.print("Please enter the year: ");
            String year = input.nextLine();
            System.out.print("Please enter the page count: ");
            String pageCount = input.nextLine();
            System.out.print("Please enter the genre: ");
            String genre = input.nextLine();
            bookClass book = new bookClass(title, author, year, pageCount, genre);
            books1DArray[0] = book.getTitle();
            books1DArray[1] = book.getAuthor();
            books1DArray[2] = book.getYear();
            books1DArray[3] = book.getPageCount();
            books1DArray[4] = book.getGenre();

        }
        for (String[] books1DArray: books2DArray) {
            printSummary( books1DArray[0], books1DArray[1], books1DArray[2], books1DArray[3], books1DArray[4]);
        }
        System.out.println("There are" + book.getBookCount() + "books in the system");
    }

    public static void printSummary(String title, String author, String year, String pageCount, String genre) {
        System.out.format("%s written by %s was published in %s, has %s pages and is of the %s genre", title, author, year, pageCount, genre);

    }

}

我有多个问题:

在主类中创建数组会更好吗？

我觉得我的效率非常低，因为感觉就像我在代码中一遍又一遍地重复自己。一些冗余对于良好的实践是必要的(例如 getter 和 setter)，但我是否做得太过分了？

在主类的 for 循环中，我想创建多个对象并将它们添加到数组中，但我不确定如何执行此操作，因为它需要不同的名称以避免被覆盖。

此外，在我的主类末尾调用 getBookCount 不起作用。这有什么原因吗？

如果您有任何一般性建议或您可能注意到的其他事情，我将不胜感激，因为我觉得我从根本上误解了 Java 类的使用。

Answer 1

你正在学习Java，所以你应该学习Java name conventions .

我假设您的图书类 public class BookClass，您可以编写使用 1 个 BookClass 数组(或 ArrayList 或任何您想要的集合类型)，例如(跳过输入检查)

public class BookTest {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);
        System.out.print("How many books would you like to enter: ");
        int bookAmount = input.nextInt(); input.nextLine();
        BookClass[] books = new BookClass[bookAmount];

        for (int i = 0; i < bookAmount; i++) {
            System.out.print("Please enter the title: ");
            String title = input.nextLine();
            System.out.print("Please enter the author ");
            String author = input.nextLine();
            System.out.print("Please enter the year: ");
            String year = input.nextLine();
            System.out.print("Please enter the page count: ");
            String pageCount = input.nextLine();
            System.out.print("Please enter the genre: ");
            String genre = input.nextLine();
            books[i] = new BookClass(title, author, year, pageCount, genre);
        }
        for (BookClass book : books) {
            printSummary(book.getTitle(), book.getAuthor(), book.getYear(), book.getPageCount(), book.getGenre());
        }
        System.out.println("There are" + books.length + "books in the system");
    }

    public static void printSummary(String title, String author, String year, String pageCount, String genre) {
        System.out.format("%s written by %s was published in %s, has %s pages and is of the %s genre", title, author, year, pageCount, genre);
    }

}

您不需要 BookClass 中的静态属性来存储书籍数量，您有很多方法可以做到这一点。

您的getBookCount不起作用，因为您调用了在侧for循环中定义的未定义参数book。如果需要，您应该定义一个静态 getter 方法 public static int getBookCount()，并访问它 BookClass.getBookCount()。但我建议你不要用它来计算对象，因为当你删除对象时，它可能会在复杂的程序中出错，使用多线程而不同步......