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枚举就是让某个变量的取值只能为若干个固定值中的一个,否则编译就会出错。
用普通类实现枚举功能:
1、私有的构造方法
2、每个元素分别用一个公有的静态成员变量表示。
3、可以有若干个公有方法或抽象方法。
定义一个WeekDay类:
1 public class WeekDay { 2 private WeekDay() { 3 } 4 5 public final static WeekDay Mon = new WeekDay(); 6 public final static WeekDay Tue = new WeekDay(); 7 public final static WeekDay Wed = new WeekDay(); 8 public final static WeekDay Thu = new WeekDay(); 9 public final static WeekDay Fri = new WeekDay(); 10 11 public WeekDay nextDay() { 12 13 if (this == Mon) { 14 return Tue; 15 } else if (this == Tue) { 16 return Wed; 17 } else if (this == Wed) { 18 return Thu; 19 } else { 20 return Fri; 21 } 22 23 24 } 25 public String toString(){ 26 if(this==Mon) return "星期一"; 27 if(this==Tue) return "星期二"; 28 if(this==Wed) return "星期三"; 29 if(this==Thu) return "星期四"; 30 if(this==Fri) return "星期五"; 31 return "不在范围内"; 32 } 33 34 }
4.产生一个测试类:
1 public class enumTest { 2 public static void main(String[] args) { 3 WeekDay weekDay = WeekDay.Mon; 4 System.out.println(weekDay.nextDay()); 5 } 6 7 }