Question

1. Design a ship class that has the following data fields:
   • A data field for the name of the ship (a string).
   • A data field for the year that the ship was built (a String).
   • A constructor and appropriate accessors and mutators.
   • A toString method that displays the ship’s name and the year it was built.
2. Design a CruiseShip class that extends the Ship class. The CruiseShip class should have the following member:
   • A field for the maximum number of passengers (an int).
   • A constructor and appropriate accessors and mutators.
   • A toString method that overrides the toString method in the base class. The CruiseShip class's toString method should display only the ships name and the maximum number of passengers.
3. Design a CargoShip class that extends the Ship class. The CargoShip class should have the following members:
   • A field for the cargo capacity in tonnage (an int).
   • A constructor and appropriate accessors and mutators.
   • A toString method that overrides the toString method in the base class. The CargoShip class's toString method should display only the ships name and ship’s cargo capacity.
4. Demonstrate the classes in a program that has a Ship array.  Assign various Ship, CruiseShip, and CargoShip objects to the array elements. The program should then step through the array, calling each objects toString method.

Answer 1

//Java code

//ship class
public class Ship {
    /**
     * A data field for the name of the ship (a string).*/
    private String shipName;
     /*
     A data field for the year that the ship was built (a String).
     */
     private String year;
    /**
     * A constructor
     */
    public Ship(String shipName, String year) {
        this.shipName = shipName;
        this.year = year;
    }

    /**
     * accessors and mutators.
     */
    public String getShipName() {
        return shipName;
    }

    public void setShipName(String shipName) {
        this.shipName = shipName;
    }

    public String getYear() {
        return year;
    }

    public void setYear(String year) {
        this.year = year;
    }
    /**
     * A toString method that displays
     * the ship’s name and the year it was built.
     */
    @Override
    public String toString() {
        return "Ship's Name: "+shipName+" and the year "+ shipName+" was built: "+year;
    }
}

//==============================

/**
 * Design a CruiseShip class that extends the Ship class.
 */
public class CruiseShip extends Ship{
    /**
     * A field for the maximum number of passengers (an int).
     */
    private int maximumPassenger;

    //Constructor

    public CruiseShip(String shipName, String year, int maximumPassenger) {
        super(shipName, year);
        this.maximumPassenger = maximumPassenger;
    }

    //Accessor and mutator

    public int getMaximumPassenger() {
        return maximumPassenger;
    }

    public void setMaximumPassenger(int maximumPassenger) {
        this.maximumPassenger = maximumPassenger;
    }
    /**
     * A toString method that overrides the toString method in the base class. The CruiseShip class's toString method should
     * display only the ships name and the maximum number of passengers.
     */
    @Override
    public String toString() {
        return "Ship's Name: "+getShipName()+"\nMaximum number of passenger: "+maximumPassenger;
    }
}

//===================================================

/**
 * Design a CargoShip class that extends the Ship class
 */
public class CargoShip extends Ship {
    /**
     * A field for the cargo capacity in tonnage (an int).
     */
    private int cargoCapacity;

    //Constructor

    public CargoShip(String shipName, String year, int cargoCapacity) {
        super(shipName, year);
        this.cargoCapacity = cargoCapacity;
    }

    //Accessor and mutator


    public int getCargoCapacity() {
        return cargoCapacity;
    }

    public void setCargoCapacity(int cargoCapacity) {
        this.cargoCapacity = cargoCapacity;
    }
    /**
     * A toString method that overrides the toString method in the base class. The CargoShip class's toString method
     * should display only the ships name and ship’s cargo capacity.
     */
    @Override
    public String toString() {
        return "Ship's Name: "+getShipName()+"\nCapacity: "+cargoCapacity+" tonnes.";
    }
}

//==================================

public class ShipDriver {
    public static void main(String[] args)
    {
        //Create array of object
        Ship[] ships = new Ship[3];
        ships[0] = new Ship("Common ship","2000");
        ships[1] = new CruiseShip("Cruise Ship","2010",150);
        ships[2] = new CargoShip("Cargo ship","2015",20000);

        //Now print info
        for (Ship s:ships
             ) {
            System.out.println(s);
        }
    }
}

//Output

//If you need any help regarding this solution ......... please leave a comment ....... thanks