案例：自定义Book类，里面包含name和price，按price排序(从大到小)。要求使用两种方式排序，有一个 Book[] books= 4本书对象。
使用前面学习过的传递实现Comparator接口匿名内部类，也称为定制排序。可以按照price (1)从大到小〔2)从小到大(3）按照书名长度从大到小

public class ArrayExercise {
    public static void main(String[] args) {
        Book[] books = new Book[4];

        books[0] = new Book("红楼梦", 100);
        books[1] = new Book("金瓶梅新", 90);
        books[2] = new Book("青年文摘2023", 5);
        books[3] = new Book("java从入门到放弃", 300);
        //
        Arrays.sort(books, new Comparator() {
            // 这里是对Book数组排序，因此o1和o2就是Book对象
            @Override
            public int compare(Object o1, Object o2) {
                Book book1 = (Book) o1;
                Book book2 = (Book) o2;
                double pdiff = book2.getPrice()-book1.getPrice();
                //这里进行了一个转换
                if(pdiff > 0) {//如果发现结果和我们输出的不一致，就修改一下返回的1和-1
                    return -1;
                } else if(pdiff < 0) {
                    return 1;
                } else {
                    return 0;
                }
             }
        });
        System.out.println(Arrays.toString(books));
    }
}

class Book {
    private String name;
    private int price;

    public Book(String name, int price) {
        this.name = name;
        this.price = price;
    }
    
    public int getPrice() {
        return price;
    }

    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}