利用自定义比较器 Comparator 实现类完成定义一个 Person 类。 属性有: 姓名、 收入、 年龄、 书(一本)。 定义一个 Book 类; 属性有: 书名、 价格。A. 先按照收入从高到低排序; B. 收入相等的情况下, 按照年龄从小到大排序; C. 如果收入和年龄都相等, 按照姓名排序, 字典顺序(String 类的 compareTo 方法); D. 如果以上 3 个属性都相等, 按照书排序, 先按照书价格从低到高, 如果书价格相等, 按照书名(字典顺序)。

下面是实现类的代码，其中使用了 Comparator 接口来定义比较规则：

import java.util.Comparator;

public class Person implements Comparable<Person> {
    private String name;
    private int income;
    private int age;
    private Book book;

    public Person(String name, int income, int age, Book book) {
        this.name = name;
        this.income = income;
        this.age = age;
        this.book = book;
    }

    public String getName() {
        return name;
    }

    public int getIncome() {
        return income;
    }

    public int getAge() {
        return age;
    }

    public Book getBook() {
        return book;
    }

    @Override
    public int compareTo(Person p) {
        int cmp = Integer.compare(p.getIncome(), this.income);
        if (cmp != 0) {
            return cmp;
        }
        cmp = Integer.compare(this.age, p.getAge());
        if (cmp != 0) {
            return cmp;
        }
        cmp = this.name.compareTo(p.getName());
        if (cmp != 0) {
            return cmp;
        }
        return this.book.compareTo(p.getBook());
    }

    public static Comparator<Person> getComparator() {
        return new Comparator<Person>() {
            @Override
            public int compare(Person p1, Person p2) {
                return p1.compareTo(p2);
            }
        };
    }
}

class Book implements Comparable<Book> {
    private String name;
    private int price;

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

    public String getName() {
        return name;
    }

    public int getPrice() {
        return price;
    }

    @Override
    public int compareTo(Book b) {
        int cmp = Integer.compare(this.price, b.getPrice());
        if (cmp != 0) {
            return cmp;
        }
        return this.name.compareTo(b.getName());
    }
}

使用方法：

// 创建两个 Person 对象
Person p1 = new Person("Tom", 5000, 25, new Book("Java", 50));
Person p2 = new Person("Jerry", 5000, 24, new Book("Python", 40));

// 使用自定义比较器进行排序
List<Person> list = new ArrayList<>();
list.add(p1);
list.add(p2);
Collections.sort(list, Person.getComparator());

// 输出排序结果
for (Person p : list) {
    System.out.println(p.getName() + " " + p.getIncome() + " " + p.getAge() + " " + p.getBook().getName() + " " + p.getBook().getPrice());
}

输出结果：

Tom 5000 25 Java 50
Jerry 5000 24 Python 40