Question

This question demonstrates the use of inheritance and polymorphism.
Design a Ship class that has 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 overrides the toString method in the Object class. The Ship class
toString method should display 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.
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 and print each object.

PLEASE DO THE QUESTION IN A SIMPLER WAY

Answer 1

Code

Ship class

public class Ship {
   private String name;
   private String year;
   /**
   * @param name
   * @param year
   */
   public Ship(String name, String year) {
       super();
       this.name = name;
       this.year = year;
   }
   /**
   * @return the name
   */
   public String getName() {
       return name;
   }
   /**
   * @param name the name to set
   */
   public void setName(String name) {
       this.name = name;
   }
   /**
   * @return the year
   */
   public String getYear() {
       return year;
   }
   /**
   * @param year the year to set
   */
   public void setYear(String year) {
       this.year = year;
   }
   /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
   @Override
   public String toString() {
       return "Ship\nName:" + name + "\nYear Built: " + year;
   }
  
  
}

CruiseShip class

public class CruiseShip extends Ship{
   private int numPasanger;

   /**
   * @param name
   * @param year
   * @param numPasanger
   */
   public CruiseShip(String name, String year, int numPasanger) {
       super(name, year);
       this.numPasanger = numPasanger;
   }

   /**
   * @return the numPasanger
   */
   public int getNumPasanger() {
       return numPasanger;
   }

   /**
   * @param numPasanger the numPasanger to set
   */
   public void setNumPasanger(int numPasanger) {
       this.numPasanger = numPasanger;
   }

   /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
   @Override
   public String toString() {
       return "Cruise "+super.toString()+"\nMaximum number of passengers: " + numPasanger;
   }
  
  
}

CargoShip class

public class CargoShip extends Ship{
   private int capacity;

   /**
   * @param name
   * @param year
   * @param capacity
   */
   public CargoShip(String name, String year, int capacity) {
       super(name, year);
       this.capacity = capacity;
   }

   /**
   * @return the capacity
   */
   public int getCapacity() {
       return capacity;
   }

   /**
   * @param capacity the capacity to set
   */
   public void setCapacity(int capacity) {
       this.capacity = capacity;
   }

   /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
   @Override
   public String toString() {
       return "Cargo "+super.toString()+"\nCapacity: " + capacity + " tones";
   }
  
}

ShipTest.java contains main method

public class ShipTest {

   public static void main(String[] args) {
       Ship shipArray[]=new Ship[3];
      
       shipArray[0]=new Ship("Samish", "2000");
       shipArray[1]=new CruiseShip("Titanic", "1954",1400);
       shipArray[2]=new CargoShip("HMM Copenhagen", "2020",1000);
              
       for(int i=0;i<shipArray.length;i++)
           System.out.println(shipArray[i]+"\n");
   }

}

output

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