enum Signal { |
GREEN, YELLOW, RED |
} |
public class TrafficLight { |
Signal color = Signal.RED; |
public void change() { |
switch (color) { |
case RED: |
color = Signal.GREEN; |
break ; |
case YELLOW: |
color = Signal.RED; |
break ; |
case GREEN: |
color = Signal.YELLOW; |
break ; |
} |
} |
} |