java枚举的使用示例

public class test {
 public static void main(String[] args) {
  WeekDay w = WeekDay.MON;
  System.out.println(w);//自己会调用tostring方法
  System.out.println(w.ordinal());//打印是枚举列表第几个对象
  System.out.println(WeekDay.values().length);//一共有多少个枚举对象
 }
 public enum WeekDay{
  SAT,MON,TUE,WED,THU,FRI,SAT,
  private WeekDay(){
   System.out.println("11");
  }
  private WeekDay(int a){
   System.out.println("a");
  }
 }
}

public enum TrefficLamp{
  RED(30){//红灯对象调用参数为int型的构造方法，
   public TrefficLamp nextLamp(){
    return GREEN;
   }
  },
  GREEN(20){
   public TrefficLamp nextLamp(){
    return YELLOW;
   }
  },
  YELLOW(2){
   public TrefficLamp nextLamp(){
    return RED;
   }
  };
  public abstract TrefficLamp nextLamp();
  private int time;
  private TrefficLamp(int time){
   this.time = time;
  };
 }