j2pp(4-7).txt

java2 primer plus一书源程序

    public static void main( String[] args )
    {
        Pinto p = new Pinto();
        System.out.println( "My car: " + p );
        p.start();
        if( p.isRunning() == false )
        {
            System.out.println( "Starter failed, let's roll start it!" );
            p.rollStart();
        }
        System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                            ", Hatchback open = " + p.isHatchBackDoorOpen() );
        for( int i=0; i<20; i++ )
        {
            p.accelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                                ", Hatchback open = " + p.isHatchBackDoorOpen() );
        }
        while( p.getCurrentSpeed() > 0 ) 
        {
            p.decelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                                ", Hatchback open = " + p.isHatchBackDoorOpen() );
        }
        p.stop();
        if( p.isHatchBackDoorOpen() )
        {
            System.out.println( "Have to close the hatchback!" );
            p.closeHatchBack();
        }
    }
}

7.3
public class Car 
{
    // Transmission types
    public static final int AUTOMATIC = 0;
    public static final int TIPTRONIC = 1;
    public static final int MANUAL = 2;

    // Attributes
    protected String typeOfCar;
    protected int horsePower;
    protected int maximumSpeed;
    protected int numberOfDoors;
    protected String paint;
    protected int gasCapacity;
    protected int oilCapacity;
    protected int transmission;

    // State attributes
    protected boolean running = false;
    protected int currentSpeed;
    protected int currentGas;
    protected int currentOil;

    public Car( String typeOfCar,
                int horsePower,
                int maximumSpeed,
                int numberOfDoors,
                String paint,
                int gasCapacity,
                int oilCapacity,
                int transmission )
    {
        this.typeOfCar = typeOfCar;
        this.horsePower = horsePower;
        this.maximumSpeed = maximumSpeed;
        this.numberOfDoors = numberOfDoors;
        this.paint = paint;
        this.gasCapacity = gasCapacity;
        this.oilCapacity = oilCapacity;
        this.transmission = transmission;
    }

    public void start()
    {
        running = true;
    }

    public void stop()
    {
        running = false;
    }

    public boolean isRunning()
    {
        return running;
    }

    public void accelerate()
    {
        currentSpeed += 5;
    }

    public void decelerate()
    {
        currentSpeed -= 5;
    }

    public int getCurrentSpeed()
    {
        return currentSpeed;
    }

    public String toString()
    {
        return typeOfCar; 
    }
}

7.4
public class Porsche2 extends Car
{
    // Attributes
    private int turbos = 2;
    private boolean nos;

    // State attributes
    private boolean turbo1Engaged = false;
    private boolean turbo2Engaged = false;
    private boolean nosEnabled = false;

    public Porsche2()
    {
        super( "Porsche",
               450,
               220,
               2,
               "Yellow",
               15,
               5,
               Car.TIPTRONIC );
    }

    public void accelerate()
    {
        // Check to see if we are running or not
        if( running == false )
        {
            return;
        }

        // Create a variable representing how much we are going to 
        // accelerate this second
        int increment = 15;

        // Check the turbos; they add 5mph per second acceleration
        if( turbo1Engaged )
        {
            increment += 5;
        }
        if( turbo2Engaged )
        {
            increment += 5;
        }

        // Check the NOS; it represents 15mph per second
        if( nos )
        {
            increment += 15;
        }

        // Increment the current speed
        currentSpeed += increment;
        if( currentSpeed > maximumSpeed ) currentSpeed = maximumSpeed;
    }

    public void decelerate()
    {
        currentSpeed -= 20;
        if( currentSpeed < 0 ) currentSpeed = 0;
    }

    public void engageTurbos()
    {
        turbo1Engaged = true;
        turbo2Engaged = true;
    }

    public void disengageTurbos()
    {
        turbo1Engaged = false;
        turbo2Engaged = false;
    }

    public void engageNOS()
    {
        nos = true;
        maximumSpeed += 50;
    }

    public void disengageNOS()
    {
        nos = false;
        maximumSpeed -= 50;
    }

    public String toString()
    {
        return "A shiny new " + paint + " Porsche!";
    }

    public static void main( String[] args )
    {
        Porsche2 p = new Porsche2();
        System.out.println( "My new car: " + p );
        p.start();
        System.out.println( "Current speed: " + p.getCurrentSpeed() );
        for( int i=0; i<20; i++ )
        {
            if( i == 5 )
            {
                p.engageTurbos();
            }
            else if( i == 14 )
            {
                p.engageNOS();
            }
            p.accelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        p.disengageNOS();
        p.disengageTurbos();
        while( p.getCurrentSpeed() > 0 ) 
        {
            p.decelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        p.stop();
    }
}

7.5
public class Pinto2 extends Car
{
    // State attributes
    public boolean hatchBackDoorOpen = false;

    public Pinto2()
    {
        super( "Pinto",
               50,
               60,
               5,
               "two-tone",
               15,
               5,
               Car.MANUAL );
    }

    public void accelerate()
    {
        // Check to see if we are running or not
        if( running == false )
        {
            return;
        }

        currentSpeed += 4;
        if( currentSpeed > maximumSpeed ) 
        {                       
            currentSpeed = maximumSpeed;

            // The high speed knocked the door open!
            openHatchBack();
        }
    }

    public void decelerate()
    {
        currentSpeed -= 5;
        if( currentSpeed < 0 ) currentSpeed = 0;
    }

    public void rollStart()
    {
        running = true;
    }

    public void pushUpHill()
    {
        System.out.println( "Ouch, this thing is heavy!" );
    }
    
    public void openHatchBack()
    {
        hatchBackDoorOpen = true;
    }
    
    public void closeHatchBack()
    {
        hatchBackDoorOpen = false;
    }

    public boolean isHatchBackDoorOpen()
    {
        return hatchBackDoorOpen;
    }

    public static void main( String[] args )
    {
        Pinto2 p = new Pinto2();
        System.out.println( "My car: " + p );
        p.start();
        if( p.isRunning() == false )
        {
            System.out.println( "Starter failed, let's roll start it!" );
            p.rollStart();
        }
        System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                            ", Hatchback open = " + p.isHatchBackDoorOpen() );
        for( int i=0; i<20; i++ )
        {
            p.accelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                                ", Hatchback open = " + p.isHatchBackDoorOpen() );
        }
        while( p.getCurrentSpeed() > 0 ) 
        {
            p.decelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() + 
                                ", Hatchback open = " + p.isHatchBackDoorOpen() );
        }
        p.stop();
        if( p.isHatchBackDoorOpen() )
        {
            System.out.println( "Have to close the hatchback!" );
            p.closeHatchBack();
        }
    }
}

7.6
public abstract class Car2 
{
    // Transmission types
    public static final int AUTOMATIC = 0;
    public static final int TIPTRONIC = 1;
    public static final int MANUAL = 2;

    // Attributes
    protected String typeOfCar;
    protected int horsePower;
    protected int maximumSpeed;
    protected int numberOfDoors;
    protected String paint;
    protected int gasCapacity;
    protected int oilCapacity;
    protected int transmission;

    // State attributes
    protected boolean running = false;
    protected int currentSpeed;
    protected int currentGas;
    protected int currentOil;

    public Car2( String typeOfCar,
                 int horsePower,
                 int maximumSpeed,
                 int numberOfDoors,
                 String paint,
                 int gasCapacity,
                 int oilCapacity,
                 int transmission )
    {
        this.typeOfCar = typeOfCar;
        this.horsePower = horsePower;
        this.maximumSpeed = maximumSpeed;
        this.numberOfDoors = numberOfDoors;
        this.paint = paint;
        this.gasCapacity = gasCapacity;
        this.oilCapacity = oilCapacity;
        this.transmission = transmission;
    }

    public void start()
    {
        running = true;
    }

    public void stop()
    {
        running = false;
    }

    public boolean isRunning()
    {
        return running;
    }

    public abstract void accelerate();

    public abstract void decelerate();

    public int getCurrentSpeed()
    {
        return currentSpeed;
    }

    public String toString()
    {
        return typeOfCar; 
    }
}

7.7
public class BadCar extends Car2
{
}

7.8
public class Driver1
{
    public void drivePorsche( Porsche2 p )
    {
        System.out.println( "Driving: " + p );
        p.start();
        for( int i=0; i<10; i++ )
        {
            p.accelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        for( int i=0; i<5; i++ )
        {
            p.decelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        p.stop();
    }

    public void drivePinto( Pinto2 p )
    {
        System.out.println( "Driving: " + p );
        p.start();
        for( int i=0; i<10; i++ )
        {
            p.accelerate();
            p.rollStart();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        for( int i=0; i<5; i++ )
        {
            p.decelerate();
            System.out.println( "Current speed: " + p.getCurrentSpeed() );
        }
        p.stop();
    }

    public static void main( String[] args )
    {
        Driver1 d = new Driver1();

        Porsche2 porsche = new Porsche2();
        d.drivePorsche( porsche );
        Pinto2 pinto = new Pinto2();
        d.drivePinto( pinto );
    }
}

7.9
public class Driver2
{
    public void drive( Car c )
    {
        System.out.println( "Driving: " + c );
        c.start();
        for( int i=0; i<10; i++ )
        {
            c.accelerate();
            System.out.println( "Current speed: " + c.getCurrentSpeed() );
        }
        for( int i=0; i<5; i++ )
        {
            c.decelerate();
            System.out.println( "Current speed: " + c.getCurrentSpeed() );
        }
        c.stop();
    }

    public static void main( String[] args )
    {
        Driver2 d = new Driver2();

        Porsche2 porsche = new Porsche2();
        d.drive( porsche );
        Pinto2 pinto = new Pinto2();
        d.drive( pinto );
    }
}