Question

Program Challenge 10

Design a Ship class that the following members:

·         A field for the name of the ship (a string).

·         A 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.

Design a CruiseShip class that extends the Ship class. The CruiseShip class should have the following members:

·         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 ship’s name and the maximum number of passengers.

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 ship’s name and the ship’s cargo capacity.

Implement programming challenge 10. Demonstrate the classes in a separate ShipDemo.java that:

1. Create an inventory of ships owned by a company from a data file.

2. Print out the ship inventory.

3. Compute and print out the total number of people the company can evacuate in a disaster with all of its appropriate ships and the total tonnage of personal belongings that the company can carry for the evacuees.

4. Must demonstrate the use of inheritance and polymorphism: define an array of Ship to track the inventory.

5. The totals in the output are to be calculated in main method of ShipDemo.

6. Each of the detail line about the ship is returned from toString. ie. for cargo, String.format “%-20s Cargo:%d”

7. The Default data file name is myShips.txt. If a file is specified in the first command line, then that name will be used. The format of the data file:

Company name:String

# of ship:int

type:char Ship name:String yearbuilt:String param:int

…

Example

All American Shipping Company

2

c Liberty 2010 100

C Challenger 2001 20000

For the name:String, the underscore character is used for space and must be converted before use. The type is case sensitive can be ‘c’ for Cruiseship and ‘C’ for CargoShip. Exception handling of file not found is mandatory, data validation, optional.

Required Output:

blank line

Welcome to Ship by your-name

blank line

Ship name Type

-------------------- ---------------

Liberty Cruise:100

American Challenger Cargo:1000

…

Total Ships = #

Total Passengers = #

Total Tonnage = #

Reading in the inventory should be in the main method of this class.

This class maintains the inventory of ship

main:

String companyName;

Ship[] shipInventory;

Open myShips.txt

Read in the company name

Read in the number of ships

Loop the number of ships

Read each ship information and add to the inventory

Print the report

The instanceof operator can be used for this:

Ship[] myShips = { new CruiseShip(…), new CargoShip(…), … };

for (Ship ship : myShips) {

if (ship[i] instanceof CruiseShip) {

        // ship[i] reference a CruiseShip

}

}

You will need this to compute the total passengers and total tonnage

Answer 1

//Ship.java

public class Ship {

      

       private String name;

       private int year;

      

       public Ship(String name, int year)

       {

             this.name = name;

             this.year = year;

       }

      

       public void setName(String name)

       {

             this.name = name;

       }

      

       public void setYear(int year)

       {

             this.year = year;

       }

      

       public String getName()

       {

             return name;

       }

      

       public int getYear()

       {

             return year;

       }

      

       public String toString()

       {

             return String.format("%-20s : %d",name,year);

       }

}

//end of Ship.java

//CruiseShip.java

public class CruiseShip extends Ship{

      

       private int num_passengers;

      

       public CruiseShip(String name, int year, int num_passengers) {

             super(name, year);

             this.num_passengers = num_passengers;

       }

      

       public void setPassengers(int num_passengers)

       {

             this.num_passengers = num_passengers;

       }

      

       public int getPassengers()

       {

             return num_passengers;

       }

      

       public String toString()

       {

             return String.format("%-20s : %d",getName()+" Cruise",num_passengers);

       }

}

//end of CruiseShip.java

//CargoShip.java

public class CargoShip extends Ship{

       private int tonnage;

      

       public CargoShip(String name, int year, int tonnage) {

             super(name, year);

             this.tonnage = tonnage;

       }

      

       public void setTonnage(int tonnage)

       {

             this.tonnage = tonnage;

       }

      

       public int getTonnage()

       {

             return tonnage;

       }

      

       public String toString()

       {

             return String.format("%-20s : %d",getName()+" Cargo",tonnage);

       }

}

//end of CargoShip.java

//ShipDemo.java

import java.io.File;

import java.io.FileNotFoundException;

import java.util.Scanner;

public class ShipDemo {

       public static void main(String[] args) {

            

             String companyName;

             int num_ships, total_passengers=0, total_tonnage=0;

             Ship[] shipInventory;

             try {

                    if(args.length == 1)

                    {

                           File file = new File(args[0]);

                           Scanner fileScan = new Scanner(file);

                           companyName = fileScan.nextLine();

                           num_ships = fileScan.nextInt();

                           shipInventory = new Ship[num_ships];

                           int n=0;

                           String type,name;

                           int value,year;

                           System.out.println("\nWelcome to ship by your-name");

                           System.out.printf("\n %-20s","Ship name Type");

                           System.out.println("\n-------------------------------");

                           while(fileScan.hasNextLine() && n<num_ships)

                           {

                                 type = fileScan.next();

                                 name = fileScan.next();

                                

                                 year = fileScan.nextInt();

                                 value = fileScan.nextInt();

                                

                                 if(type.equals("c"))

                                 {

                                        shipInventory[n] = new CruiseShip(name.replaceAll("_", " "),year,value);

                                       

                                 }else if(type.equals("C"))

                                 {

                                        shipInventory[n] = new CargoShip(name.replaceAll("_", " "),year,value);

                                 }

                                 n++;

                           }

                          

                           for (Ship ship : shipInventory)

                           {

                                 if (ship instanceof CruiseShip)

                                 {

                                        total_passengers += ((CruiseShip) ship).getPassengers();

                                        System.out.println(((CruiseShip) ship));

                                 }else

                                 {

                                        total_tonnage += ((CargoShip) ship).getTonnage();

                                        System.out.println(((CargoShip) ship));

                                 }

                          

                           }

                          

                           System.out.println("\nTotal Ships : "+shipInventory.length);

                           System.out.println("Total Passengers : "+total_passengers);

                           System.out.println("Total Tonnage : "+total_tonnage);

                    }else

                           System.out.println(" Pass the filename from command line argument");

                   

             } catch (FileNotFoundException e) {

                    // TODO Auto-generated catch block

                    e.printStackTrace();

             }

            

       }

}

//end of ShipDemo.java

Output: