java技术系列(一) Enum

 1 package testjava;
 2 
 3 import com.alibaba.fastjson.JSON;
 4 
 5 /**
 6  * Create with test01
 7  * Auther: hp.wang on 2017/9/19
 8  * DateTime: 2017/9/19 20:16
 9  */
10 public class testEnum {
11 
12     //常用定义Enum方法
13     public enum Role {
14         ADMIN(1), GUIDER(2), ROBOT(3),USER(4);  //顺序很重要
15 
16         private int value;
17 
18         Role(int v) {
19             this.value = v;
20         }
21 
22         public int getValue() {
23             return value;
24         }
25 
26         public static Role getByValue(int v) {
27             for (Role r : Role.values()) {
28                 if (r.getValue() == v) {
29                     return r;
30                 }
31             }
32             throw new IllegalArgumentException(v + " is not found in this enum.");
33         }
34     }
35 
36     public static void main(String[] args) {
37         //使用方法：
38         Role role = Role.ADMIN;
39         System.out.println(role.toString() + ":" + role.getValue());
40         System.out.println(Role.getByValue(2).toString());
41         System.out.println("json:"+ JSON.toJSONString(role));
42 
43         Role role1=JSON.parseObject("\"ADMIN\"",Role.class);
44         Role role2=JSON.parseObject("\"USER\"",Role.class);
45 
46         System.out.println("end");
47     }
48 }