工具类--常量类
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
⼯具类--常量类
共有四种⽅式：
1/**
2 * Method One
3 * 定义接⼝类，采⽤接⼝(Interface)的中变量默认为static final的特性。
4*/
5interface ConstantInterface {
6 String SUNDAY = "SUNDAY";
7 String MONDAY = "MONDAY";
8 String TUESDAY = "TUESDAY";
9 String WEDNESDAY = "WEDNESDAY";
10 String THURSDAY = "THURSDAY";
11 String FRIDAY = "FRIDAY";
12 String SATURDAY = "SATURDAY";
13 }
14/**
15 * Method Two
16 * 定义枚举
17*/
18enum ConstantEnum {
19 SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
20 }
21/**
22 * Method Three
23 * 定义常量类
24*/
25class ConstantClassField {
26public static final String SUNDAY = "SUNDAY";
27public static final String MONDAY = "MONDAY";
28public static final String TUESDAY = "TUESDAY";
29public static final String WEDNESDAY = "WEDNESDAY";
30public static final String THURSDAY = "THURSDAY";
31public static final String FRIDAY = "FRIDAY";
32public static final String SATURDAY = "SATURDAY";
33 }
34/**
35 * Method Four
36 * 定义bean
37*/
38class ConstantClassFunction {
39private static final String SUNDAY = "SUNDAY";
40private static final String MONDAY = "MONDAY";
41private static final String TUESDAY = "TUESDAY";
42private static final String WEDNESDAY = "WEDNESDAY";
43private static final String THURSDAY = "THURSDAY";
44private static final String FRIDAY = "FRIDAY";
45private static final String SATURDAY = "SATURDAY";
46public static String getSunday() {
47return SUNDAY;
48 }
49public static String getMonday() {
50return MONDAY;
51 }
52public static String getTuesday() {
53return TUESDAY;
54 }
55public static String getWednesday() {
56return WEDNESDAY;
57 }
58public static String getThursday() {
59return THURSDAY;
60 }
61public static String getFirday() {
62return FRIDAY;
63 }
64public static String getSaturday() {
65return SATURDAY;
66 }
67 }
68
69/**
70 * 测试代码
71 * */
72class TestConstant {
73static final String day = "saturday";
74public static void main(String[] args) {
75 System.out.println("Is today Saturday?");
76 System.out.println(day.equalsIgnoreCase(ConstantInterface.SATURDAY));
77 System.out.println(day.equalsIgnoreCase(()));
78 System.out.println(day.equalsIgnoreCase(ConstantClassField.SATURDAY));
79 System.out.println(day.equalsIgnoreCase(ConstantClassFunction.getSaturday()));
80 }
81 }
⽅法⼀采⽤接⼝(Interface)的中变量默认为static final的特性。
⽅法⼆采⽤了Java 5.0中引⼊的Enum(枚举)类型。
⽅法三采⽤了在普通类中使⽤static final修饰变量的⽅法。
⽅法四类似⽅法三，但是通过函数来获取常量，类似bean，也就是有⾃带的get⽅法。
使⽤常量类原因：
定义全局变量会增加程序耦合成都。
最佳的⽅法是避免定义全局变量。
如果是参数等，可以写⼊配置⽂件，否则⽅法⼆是最为推荐。
⽅法三是⽐较直观。
⽅法⼀和⽅法三本质上⼀样。
⽅法四提供了灵活性。