vehicle.java

现在在国外大学里最流行的java学习软件,同时还有大量的example,在名为project的文件里.安装好后用bluej打开peoject的例子,可以进行你想要的任何变化.同时可以了解大量的源码

/**
 * Capture outline details of a vehicle.
 * 
 * @author David J. Barnes and Michael Kolling
 * @version 2006.03.30
 */
public abstract class Vehicle
{
    private TaxiCompany company;
    // Where the vehicle is.
    private Location location;
    // Where the vehicle is headed.
    private Location targetLocation;
    
    /**
     * Constructor of class Vehicle
     * @param company The taxi company. Must not be null.
     * @param location The vehicle's starting point. Must not be null.
     * @throws NullPointerException If company or location is null.
     */
    public Vehicle(TaxiCompany company, Location location)
    {
        if(company == null) {
            throw new NullPointerException("company");
        }
        if(location == null) {
            throw new NullPointerException("location");
        }
        this.company = company;
        this.location = location;
        targetLocation = null;
    }
    
    /**
     * Notify the company of our arrival at a pickup location.
     */
    public void notifyPickupArrival()
    {
        company.arrivedAtPickup(this);
    }
    
    /**
     * Notify the company of our arrival at a
     * passenger's destination.
     * @param passenger The passenger who has arrived.
     */
    public void notifyPassengerArrival(Passenger passenger)
    {
        company.arrivedAtDestination(this, passenger);
    }
    
    /**
     * Receive a pickup location.
     * How this is handled depends on the type of vehicle.
     * @param location The pickup location.
     */
    public abstract void setPickupLocation(Location location);
    
    /**
     * Receive a passenger.
     * How this is handled depends on the type of vehicle.
     * @param passenger The passenger being picked up.
     */
    public abstract void pickup(Passenger passenger);
    
    /**
     * @return Whether or not this vehicle is free.
     */
    public abstract boolean isFree();
    
    /**
     * Offload any passengers whose destination is the
     * current location.
     */
    public abstract void offloadPassenger();
    
    /**
     * @return Where this vehicle is currently located.
     */
    public Location getLocation()
    {
        return location;
    }
    
    /**
     * Set the current location.
     * @param location Where it is. Must not be null.
     * @throws NullPointerException If location is null.
     */
    public void setLocation(Location location)
    {
        if(location != null) {
            this.location = location;
        }
        else {
            throw new NullPointerException();
        }
    }
    
    /**
     * @return Where this vehicle is currently headed, or null
     *         if it is idle.
     */
    public Location getTargetLocation()
    {
        return targetLocation;
    }
    
    /**
     * Set the required target location.
     * @param location Where to go. Must not be null.
     * @throws NullPointerException If location is null.
     */
    public void setTargetLocation(Location location)
    {
        if(location != null) {
            targetLocation = location;
        }
        else {
            throw new NullPointerException();
        }
    }
    
    /**
     * Clear the target location.
     */
    public void clearTargetLocation()
    {
        targetLocation = null;
    }
}