enum的高级应用

public enum Lamp{
RED(30){
public  Lamp nextLamp(){
return GREEN;
}
},
GREEN(45){
public  Lamp nextLamp(){
return YELLOW;
}
},
YELLOW(5){
public  Lamp nextLamp(){
return RED;
}
};
public abstract Lamp nextLamp();
private int time;
private Lamp (int time){this.time = time;}
}