// Robot uses the built-in Color class in java.awt.Color.  (see Java API)
import java.awt.Color; 

/**   BouncingRobot is a Robot which bounces when it hits a wall.
 *    i.e., if it can't step in a certain direction, it changes direction
 */
public class BouncingRobot extends Robot {

   // fields

   //    new state
   protected boolean movingForward = true;   // true if moving Forward, 
                                             // false if moving Backward

   // constructor

   public BouncingRobot( Stepper s, Color c ) {
      // call the superclass's constructor
      super( s, c );
   }

   /**   BouncingRobot overrides the act() method.
    *    Instead of moving forward all the time, the robot moves
    *    forward until it hits a wall and cannot step.  Then,
    *    it starts moving backward until it hits the wall, then
    *    it starts moving forward again, ... ad nauseam.
    */
   public void act()
   {
      if (movingForward) {
         try {
            // try to step forward
            myStepper.stepForward();
         } catch (CannotStepException e) {
            // if it's not possible, then next time try moving backward
            movingForward = false;
         }
      } else {
         try {
            // try to step backward
            myStepper.stepBackward();
         } catch (CannotStepException e) {
            // if it's not possible, then next time try moving forward
            movingForward = true;
         }

      }
   }


}