第一个枚举类-交通信号灯

package example;
//JHTP Exercise 8.10
//by pandenghuang@163.com
/**Write an enum type TrafficLight, whose constants (RED, GREEN, YELLOW) take one parameter—
the duration of the light. Write a program to test the TrafficLight enum so that it displays the
enum constants and their durations.
*/
import java.util.EnumSet;

enum TrafficLight{
RED(20),
GREEN(30),
YELLOW(3);

private int duration;

TrafficLight(int duration)
{
this.duration = duration;
}

public int getDuration()
{
return duration;
}

}

public class TrafficLightTest
{
public static void main(String[] args)
{
System.out.println("All Trafic Lights:");

for (TrafficLight tl : TrafficLight.values())
System.out.printf("%-10s%d%n", tl,
tl.getDuration());
}
}