Java——类比较器

1、Product类

 1 public class Product
 2 {
 3     private int pid;
 4     private String name;
 5     private double price;
 6 
 7     public Product()
 8     {
 9         // TODO Auto-generated constructor stub
10     }
11 
12     public Product(int pid, String name, double price)
13     {
14         this.pid = pid;
15         this.name = name;
16         this.price = price;
17     }
18 
19     public int getPid()
20     {
21         return pid;
22     }
23 
24     public void setPid(int pid)
25     {
26         this.pid = pid;
27     }
28 
29     public String getName()
30     {
31         return name;
32     }
33 
34     public void setName(String name)
35     {
36         this.name = name;
37     }
38 
39     public double getPrice()
40     {
41         return price;
42     }
43 
44     public void setPrice(double price)
45     {
46         this.price = price;
47     }
48 
49 }

2、类比较器：重写compare方法

 1 public class MyCompare implements Comparator<Product> // 泛型<Product>表示该比较器只能比较Product类型
 2 {
 3 
 4     @Override
 5     public int compare(Product p1, Product p2)
 6     {
 7         if (p1.getPrice() < p2.getPrice())
 8         {
 9             return -1;
10         }
11         else if (p1.getPrice() > p2.getPrice())
12         {
13             return 1;
14         }
15         else
16         // 如果价格一样，按照id排序
17         {
18             if (p1.getPid() < p2.getPid())
19             {
20                 return -1;
21             }
22             else if (p1.getPid() > p2.getPid())
23             {
24                 return 1;
25             }
26             else
27             {
28                 return 0;
29             }
30         }
31     }
32 
33 }

3、在ArrayList中使用比较器

 1 public class ProductSort
 2 {
 3     public static void main(String[] args)
 4     {
 5     
 6                 Product p1 = new Product(1, "爆米花手机", 1000000.00);
 7         Product p2 = new Product(2, "iPhone 7s", 5088.00);
 8         Product p3 = new Product(3, "小米5s", 1999.99);
 9         Product p4 = new Product(4, "NIIT课程", 12800.00);
10         Product p5 = new Product(5, "百达翡丽", 1980000.00);
11         Product p6 = new Product(6, "宝玛electric", 1999.99);
12         Product p7 = new Product(7, "TIIN课程", 12800.00);
13                 // 获得数组准备排序
14         Product[] proArr = { p1, p2, p3, p4, p5, p6, p7 };
15 
16         Arrays.sort(proArr, new MyCompare());
17 
18         for (Product p : proArr)
19         {
20             System.out.println(p.getPid() + " " + p.getName() + " "
21                     + p.getPrice());
22         }
23     }
24 }