Java对象数组似乎为空

Question

我在使用学校 Java 程序时遇到问题，您能帮我吗？ 该程序应该让你在输入中给他一些书籍信息，例如每本书的标题、价格。现在我创建了一个对象数组，每个对象应该为每个选项都有一个私有(private)变量(使用方法 setter 进行设置并使用方法 getter 进行声明)。 问题是我不知道错误在哪里，但程序在输出中仅打印最后一个变量，即价格。其他的都为空。 请问你能帮帮我吗？ 主要:

    class Esercizio2
{
    public static void main(String[] args)
    {
        // Objects
        ConsoleReader2 keyboard = new ConsoleReader2(System.in);
        // Init
        int n = 0;  // book number
        // temp variables
        String title;
        String writer;
        String house;
        String price;
        // Calc
        System.out.println("How many books you wanna analyze?");
        do
        {
            n = keyboard.readInt();
            if (n <= 0)
            {
                System.out.print("You've inserted a negative or 0 number, you have to input a positive number, try again ===> ");
            }
        }
        while (n <= 0);
        // array of the books
        Libri2[] info = new Libri2[n];
        // through arrays
        for (int i = 0, j = 1; i < info.length; i++, j++)
        {
            // input title
            System.out.print("Input the title for book number " + j + " ===> ");
            title = keyboard.readLine();
            info[i] = new Libri2();
            info[i].setTitle(title);
            // input writer
            System.out.print("Input the writer for book number " + j + " ===> ");
            writer = keyboard.readLine();
            info[i] = new Libri2();
            info[i].setWriter(writer);
            // input house
            System.out.print("Input the house for book number " + j + " ===> ");
            house = keyboard.readLine();
            info[i] = new Libri2();
            info[i].setHouse(house);
            // input price
            System.out.print("Input the price for book number " + j + " ===> ");
            price = keyboard.readLine();
            info[i] = new Libri2();
            info[i].setPrice(price);
        }
        // Declaration
        for (int i = 0, j = 1; i < info.length; i++, j++)
        {
            System.out.print("The title of book number " + j + " is  ===> " + info[i].getTitle() + "\n");
            System.out.println("His features are:\n" + info[i].getWriter() + "\n" + info[i].getHouse() + "\n" + info[i].getPrice());
        }
    }
}

ConsoleReader2 是我用来代替 Scanner 的类，但它是相同的，readLine 是输入字符串的方法。 具有 setter 和 getter 方法的类:

    public class Libri2
{
    // attributs:
    private String title;
    private String writer;
    private String house;
    private String price;
    // methods: (setter e getter)
    // give title
    public String getTitle()
    {
        return this.title;
    }
    // set title
    public void setTitle(String m)
    {
        this.title = m;
    }
    // give writer
    public String getWriter()
    {
        return this.writer;
    }
    // set writer
    public void setWriter(String m)
    {
        this.writer = m;
    }
    // give house
    public String getHouse()
    {
        return this.house;
    }
    // set house
    public void setHouse(String m)
    {
        this.house = m;
    }
    // give price
    public String getPrice()
    {
        return this.price;
    }
    // set price
    public void setPrice(String m)
    {
        this.price = m;
    }
}

Answer 1

每次设置属性时，您都会重新创建并重置当前元素，就像这样

info[i] = new Libri2();

给您留下一组仅包含价格的对象。