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Comparable和Comparator排序接口

news 来源：原创 2024/5/3 22:09:57

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
 *    1784186573@qq.com
 */
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

 1 package comparatest1;
 2 
 3 public class Person implements Comparable<Person>{
 4     private String name;
 5     private int money;
 6     private int age;
 7     private Book book;
 8     public Person(String name, int money, int age, Book book) {
 9         super();
10         this.name = name;
11         this.money = money;
12         this.age = age;
13         this.book = book;
14     }
15     public String getName() {
16         return name;
17     }
18     public void setName(String name) {
19         this.name = name;
20     }
21     public int getMoney() {
22         return money;
23     }
24     public void setMoney(int money) {
25         this.money = money;
26     }
27     public int getAge() {
28         return age;
29     }
30     public void setAge(int age) {
31         this.age = age;
32     }
33     public Book getBook() {
34         return book;
35     }
36     public void setBook(Book book) {
37         this.book = book;
38     }
39     @Override
40     public int compareTo(Person o) {
41         int m=-Integer.valueOf(money).compareTo(Integer.valueOf(o.money));
42         int a=Integer.valueOf(age).compareTo(Integer.valueOf(o.age));
43         int n=name.compareTo(o.name);
44         int b=book.compareTo(o.book);
45         return (m!=0?m:(a!=0?a:(n!=0?n:b)));
46     }
47     
48     @Override
49     public int hashCode() {
50         final int prime = 31;
51         int result = 1;
52         result = prime * result + age;
53         result = prime * result + ((book == null) ? 0 : book.hashCode());
54         result = prime * result + money;
55         result = prime * result + ((name == null) ? 0 : name.hashCode());
56         return result;
57     }
58     @Override
59     public boolean equals(Object obj) {
60         if (this == obj)
61             return true;
62         if (obj == null)
63             return false;
64         if (getClass() != obj.getClass())
65             return false;
66         Person other = (Person) obj;
67         if (age != other.age)
68             return false;
69         if (book == null) {
70             if (other.book != null)
71                 return false;
72         } else if (!book.equals(other.book))
73             return false;
74         if (money != other.money)
75             return false;
76         if (name == null) {
77             if (other.name != null)
78                 return false;
79         } else if (!name.equals(other.name))
80             return false;
81         return true;
82     }
83     @Override
84     public String toString() {
85         return "Person [name=" + name + ", money=" + money + ", age=" + age
86                 + ", book=" + book + "]";
87     }
88     
89 }

Book类

 1 package comparatest1;
 2 
 3 public class Book implements Comparable<Book> {
 4     private String name;
 5     private int price;
 6 
 7     public Book(String name, int price) {
 8         super();
 9         this.name = name;
10         this.price = price;
11     }
12 
13     public String getName() {
14         return name;
15     }
16 
17     public void setName(String name) {
18         this.name = name;
19     }
20 
21     public int getPrice() {
22         return price;
23     }
24 
25     public void setPrice(int price) {
26         this.price = price;
27     }
28 
29     @Override
30     public int compareTo(Book o) {
31         int p=Integer.valueOf(price).compareTo(Integer.valueOf(o.price));
32         int n=name.compareTo(o.name);
33         return (p!=0 ? p : n);
34     }
35 
36     @Override
37     public int hashCode() {
38         final int prime = 31;
39         int result = 1;
40         result = prime * result + ((name == null) ? 0 : name.hashCode());
41         result = prime * result + price;
42         return result;
43     }
44 
45     @Override
46     public boolean equals(Object obj) {
47         if (this == obj)
48             return true;
49         if (obj == null)
50             return false;
51         if (getClass() != obj.getClass())
52             return false;
53         Book other = (Book) obj;
54         if (name == null) {
55             if (other.name != null)
56                 return false;
57         } else if (!name.equals(other.name))
58             return false;
59         if (price != other.price)
60             return false;
61         return true;
62     }
63 
64     @Override
65     public String toString() {
66         return "Book [name=" + name + ", price=" + price + "]";
67     }
68 
69 }