java enum

public class EnumTest {
	
	public static void main(String[] args) {
		WeekDay weekDay = WeekDay.MON;
		System.out.println(weekDay.nextDay());
		
		
		WeekDays w = WeekDays.FRI;
		
		// enum 已重写了toString()方法
		System.out.println(w);
		
		// 子类实现父类的带参构造方法
	//	new Date(300){}
		
	}
	
	/**
	 * 枚举只有一个成员时,就可以作为一个单例的实现方式.
	 */

		
	/**
	 * 定义枚举
	 * 
	 * 
	 * 实现带有构造方法的枚举
	 * 
	 * 
	 * 实现带有抽象方法的枚举
	 */	
	public enum WeekDays{
		
		SUN(3),MON,TUE,WED,THI,FRI,SAT;
		
		/**
		 * only private constructor
		 */
		private WeekDays(){}
		
		private WeekDays(int day){}
	}
	
	/**
	 * 实现带有构造方法的枚举
	 */
	
	
	/**
	 * 实现带有抽象方法的枚举
	 * 
	 * 实现交通信号灯
	 */
	
	public enum TrafficLamp{
		
		RED(30) {
			@Override
			public TrafficLamp nextLamp() {
				return GREEN;
			}
		},GREEN(15) {
			@Override
			public TrafficLamp nextLamp() {
				return YELLOW;
			}
		},YELLOW(5) {
			@Override
			public TrafficLamp nextLamp() {
				return RED;
			}
		};
		
		public abstract TrafficLamp nextLamp();
		
		// 时间
		private int time;
		
		private TrafficLamp(int time){
			this.time = time;
		}
		
		private TrafficLamp(){}
	}