public abstract class Vehicle {   protected ParkingSpace pSpace;   public abstract boolean park(ParkingLot pLot);   public boolean unpark(ParkingLot pLot)P{       if(pSpace!=null){           pLot.reclaimFreeSpace(pSpace);           return true;       }       return false;   }}public class Cars extends Vehicle{    @Override    public boolean park(ParkingLot pLot) {        if( (pSpace = pLot.allocateFreeSpace(ParkingSpace.ParkingSpaceType.CAR)) ==null)            return true;        else            return false;    }    }public class Motorbike extends Vehicle{    @Override    public boolean park(ParkingLot pLot) {        if( (pSpace = pLot.allocateFreeSpace(ParkingSpace.ParkingSpaceType.MOTOBIKE)) ==null)            return true;        else            return false;    }    }public class HandicappedCars extends Vehicle{    @Override    public boolean park(ParkingLot pLot) {        if( (pSpace = pLot.allocateFreeSpace(ParkingSpace.ParkingSpaceType.HANDICAPPED)) ==null)            return true;        else            return false;    }}import java.sql.Time;import java.util.GregorianCalendar;public class ParkingSpace {    public enum ParkingSpaceType    {        MOTOBIKE, CAR, HANDICAPPED;    }        private int id;    private ParkingSpaceType pSpaceType;    private ParkingMeter meter;         public ParkingSpace(int id, ParkingSpaceType pspaceType)     {            super();            this.id = id;            this.pSpaceType = pspaceType;     }          public int getId()        {            return id;        }       public void setStart()        {            meter.start = new GregorianCalendar();        }        public void setEnd()        {            meter.end = new GregorianCalendar();        }             public ParkingSpaceType getpSpaceType(){         return pSpaceType;     }          private class ParkingMeter{         public GregorianCalendar start;         public GregorianCalendar end;     }           public float getFee()      {            return perm.getFee(meter.start, meter.end);      }}import java.util.List;import parking.ParkingSpace.ParkingSpaceType;public class ParkingLot {       private List<ParkingSpace> freeRegularSpace;       private List<ParkingSpace> freeCompactSpace;       private List<ParkingSpace> freeHandicappedSpace;               public ParkingLot(){};              public ParkingSpace allocateFreeSpace(ParkingSpaceType pSpaceType) throws Exception{           ParkingSpace pSpace = null;                      switch(pSpaceType)           {           case MOTOBIKE:               if(freeRegularSpace.size()==0)                   return null;               pSpace = freeRegularSpace.remove(0);               pSpace.setStart();               break;                          case HANDICAPPED:               if(freeHandicappedSpace.size()==0)                   return null;               pSpace = freeHandicappedSpace.remove(0);               pSpace.setStart();               break;                          case CAR:               if(freeCompactSpace.size()==0)                   return null;               pSpace = freeCompactSpace.remove(0);               pSpace.setStart();               break;                          default:               throw new Exception("Invalid String");           }                      public float reclainFreeSpace(ParkingSpace Space){               Space.setEnd();               switch(Space.getpSpaceType()){               case MOTOBIKE:                   freeRegularSpace.add(Space);                   break;                                  case CAR:                   freeCompactSpace.add(Space);                   break;                                  case HANDICAPPED:                   freeHandicappedSpace.add(Space);                   break;                               default:                   break;               }                              return Space.getFee();                                         }                             }}