黑马程序员_Java基础加强实现带有构造方法的枚举

实现带有构造方法的枚举，当枚举只有一个成员时，就可以作为一种单例的实现模式

public class EnumTest {      
    public static void main(String[] args) {      
        WeekDay mon = WeekDay.MON;      
        System.out.println(mon);//名称为MON       
        System.out.println(mon.name());//名称为MON       
        System.out.println(WeekDay.valueOf("YYY"));//增加枚举，将"YYY"变为枚举类型       
        System.out.println(WeekDay.values().length);//返回枚举值       
    }      
    public enum WeekDay{      
        //成员列表必须写在所有成员之前       
        SUN,MON,TUE,WED,THI,FRI,SAT;//MON和MON(1)就是表示在构造       
        private WeekDay(){}      
        private WeekDay(int day){}      
              
    }      
    public enum TrafficLamp{      
        RED(30){      
            public TrafficLamp nextLamp() {      
                return GREEN;      
            }      
        },GREEN(45){      
            public TrafficLamp nextLamp() {      
                return YELLOW;      
            }      
        },YELLOW(5){      
            public TrafficLamp nextLamp() {      
                return RED;      
            }      
        };      
        public abstract TrafficLamp nextLamp();      
        private int time;      
        private TrafficLamp(int time){      
            this.time = time;      
        }      
    }      
}