状态模式（State）

package com.designPattern.state;

public enum State {
	RED("红灯", 2000) {
		@Override
		public State change() {
			return GREEN;
		}
	},
	GREEN("绿灯", 1000) {
		@Override
		public State change() {
			return YELLOW;

		}
	},
	YELLOW("黄灯", 500) {
		@Override
		public State change() {
			return RED;
		}
	};
	private int wait;
	private String statname;

	public abstract State change();

	public State changeState() {
		System.out.println(statname);
		try {
			Thread.sleep(wait);
		} catch (InterruptedException e) {
			System.out.println("wrong");
		}
		return change();
	}

	private State(String name, int wait) {
		statname = name;
		this.wait = wait;
	}

	public String getStatname() {
		return statname;
	}

	public static void main(String[] args) {
		GREEN.changeState();
		GREEN.changeState().changeState();
		GREEN.changeState().changeState().changeState();
	}

	public void setWait(int wait) {
		this.wait = wait;
	}

	public int getWait() {
		return wait;
	}
}

enum Light{
    红灯(1000),黄灯(5000),绿灯(5000);    //顺序调整.
    int sleepping;
    private Light(int x) {
        this.sleepping = x ;        
    } 
    public Light change(){
        System.out.println(name());
        sleep();
        return next();
    }
	
    public Light next(){
        return values()[((ordinal()+1)%(values().length))];
    }
    public static void main(String[] args) {
		Light light = Light.红灯;
    	while(true){
			light = light.change();
		}
	}
    private void sleep() {
		try {
			Thread.sleep(this.sleepping);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}