Comparable和Comparator排序接口

Comparable和Comparator都是排序的接口，都可以用类来实现，排序效果一样。

Comparable一般用类来实现，就是大家所说的自然排序；

Comparator一般用来匿名实现，作为集合的比较器，也就是定制排序；

Test测类

package comparatest1;

import java.util.TreeSet;
/**
 * 
 * @author likainian
 *    [e-mail]
 */
public class Test {
    public static void main(String[] args) {
        TreeSet<Person>ts=new TreeSet<>();
        Book b1=new Book("a", 12);
        Book b2=new Book("b", 12);
        Book b3=new Book("c", 12);
        Person p1=new Person("a", 1, 1, b1);
        Person p2=new Person("a", 1, 1, b2);
        Person p3=new Person("a", 1, 1, b3);
        ts.add(p1);
        ts.add(p2);
        ts.add(p3);
        System.out.println(ts);
        
    }
}

Person类

package comparatest1;

public class Person implements Comparable<Person>{
    private String name;
    private int money;
    private int age;
    private Book book;
    public Person(String name, int money, int age, Book book) {
        super();
        this.name = name;
        this.money = money;
        this.age = age;
        this.book = book;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getMoney() {
        return money;
    }
    public void setMoney(int money) {
        this.money = money;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public Book getBook() {
        return book;
    }
    public void setBook(Book book) {
        this.book = book;
    }
    @Override
    public int compareTo(Person o) {
        int m=-Integer.valueOf(money).compareTo(Integer.valueOf(o.money));
        int a=Integer.valueOf(age).compareTo(Integer.valueOf(o.age));
        int n=name.compareTo(o.name);
        int b=book.compareTo(o.book);
        return (m!=0?m:(a!=0?a:(n!=0?n:b)));
    }
    
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + age;
        result = prime * result + ((book == null) ? 0 : book.hashCode());
        result = prime * result + money;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Person other = (Person) obj;
        if (age != other.age)
            return false;
        if (book == null) {
            if (other.book != null)
                return false;
        } else if (!book.equals(other.book))
            return false;
        if (money != other.money)
            return false;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        return true;
    }
    @Override
    public String toString() {
        return "Person [name=" + name + ", money=" + money + ", age=" + age
                + ", book=" + book + "]";
    }
    
}

Book类

package comparatest1;

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

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    @Override
    public int compareTo(Book o) {
        int p=Integer.valueOf(price).compareTo(Integer.valueOf(o.price));
        int n=name.compareTo(o.name);
        return (p!=0 ? p : n);
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        result = prime * result + price;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Book other = (Book) obj;
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
        if (price != other.price)
            return false;
        return true;
    }

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

}