标签:函数 else [] abstract 方法 new final str 抽象类
1. 使用普通类模拟枚举
1 public class Weekday { 2 private Weekday() {} // 私有化 3 4 public static final Weekday MONDAY = new Weekday(); // 每个枚举都是一个对象 5 public static final Weekday TUESDAY = new Weekday(); 6 7 public String toString() { 8 if(this == MONDAY) 9 return "Monday"; 10 else if(...) ... 11 } 12 }
2. 使用抽象类模拟枚举
1 public abstract class Weekday { 2 private Weekday() {} 3 4 public final static Weekday MONDAY = new Weekday() { 5 public Weekday nextDay() { 6 return TUESDAY; 7 } 8 }; 9 10 public final static Weekday TUESDAY = new Weekday() { 11 public Weekday nextDay() { 12 return WEDNESDAY; 13 } 14 }; 15 16 ... 17 18 public abstract Weekday nextDay(); 19 }
使用抽象类模拟可以免除写大量的if-else语句,不需要对每个对象进行判断,只需要有具体实现类完成即可
3. 枚举类
1 public enum Weekday { 2 SUN, MON, TUE, WED, THU, FRI, SAT 3 }
普通的枚举类末尾不需要写分号
4. 带构造参数枚举
1 public enum Weekday { 2 SUN(5), MON(), TUE(7), WED(), THU(9), FRI, SAT; // 必须第一行,且以分号结尾 3 4 private Weekday() {} 5 private Weekday(int number) { 6 System.out.println(number); 7 } 8 }
枚举中每个变量都是static final的
5. 带抽象函数的枚举
1 public enum Weekday { // enum不用abstract修饰 2 SUN(5) { 3 public Weekday nextDay() { 4 return MON; 5 } 6 }, 7 MON() { 8 public Weekday nextDay() { 9 return TUE; 10 } 11 }, 12 TUE() { 13 public Weekday nextDay() { 14 return WED; 15 } 16 }, 17 WED() { 18 public Weekday nextDay() { 19 return THU; 20 } 21 }, 22 THU() { 23 public Weekday nextDay() { 24 return FRI; 25 } 26 }, 27 FRI() { 28 public Weekday nextDay() { 29 return SAT; 30 } 31 }, 32 SAT() { 33 public Weekday nextDay() { 34 return SUN; 35 } 36 }; 37 38 private Weekday() {} 39 private Weekday(int number) { 40 System.out.println(number); 41 } 42 43 public abstract Weekday nextDay(); 44 }
6. 枚举类中的方法
toString() - String
name() - String
ordinal() - int
valueOf(String name) - Weekday
values() - Weekday[]
标签:函数 else [] abstract 方法 new final str 抽象类
原文地址:http://www.cnblogs.com/joshua-aw/p/6020389.html