回答1：

enum TrafficLight {  RED,  GREEN;  @Override  public String toString() {    switch(this) {      case RED: return "abc";      case GREEN: return "def";      default: throw new IllegalArgumentException();    }  }}

回答2：

enum TrafficLight {  RED(0),  GREEN(15);  int value;  TrafficLight(int value) { this.value = value; }}