Java Help with Inheritance 1- Use inheritance to implement the following classes

Question

Java Help with Inheritance 1- Use inheritance to implement the following classes: A: A Car that is a Vehicle and has a name, a max_speed value and an instance variable called the number_of_cylinders in its engine. There should be public methods to set and get the values of these variables. When a car is printed (using the toString method), its name, max_speed and number_of_cylinders are shown. B: An Airplane that is also a vehicle and has a name, a max_speed value and an instance variable called the number_of_engines it has. There should be public methods to set and get the values of these variables. When an airplane is printed (using the toString method), its name, max_speed and number_of_engines are shown. C: Write a VehicleDemo.java class that does the following: 1- Creates an instance of a Car and Airplane classes. 2- Assign values to the name, speed, number_of_cylinders (for the Car object) and number_of_engines (for the Airplane object) variables. 3- Compares which vehicle goes faster and prints the result. 4- Prints the instances of the car and airplane classes.

Explanation / Answer

/*The java Vehicle that sets the name and max speed
* and have methods to set and get methods of
* instance variables.*/
//Vehicle.java
public class Vehicle
{
   private String name;
   private double maxSpeed;

   //default constructor
   public Vehicle()
   {
       name="unknown";
       maxSpeed=0;
   }
   //Parameterized constructor
   public Vehicle(String name, double maxSpeed)
   {
       setName(name);
       setMaxSpeed(maxSpeed);
   }
  
   //Set name
   public void setName(String name)
   {
       this.name=name;
   }
   //Set max speed
   public void setMaxSpeed(double maxSpeed)
   {
       this.maxSpeed=maxSpeed;
   }
   //Returns name
   public String getName()
   {
       return name;
   }
   //Returns max speed
   public double getMaxSpeed()
   {
       return maxSpeed;
   }
  
   //Override toString method
   @Override
   public String toString() {      
       return "Name : "+name+" Max Speed : "+maxSpeed;
   }
}

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

//Car.java
//The class Car extends the vehicle class inherits the
//properties from vehicle class
public class Car extends Vehicle
{

   //instance variable
   private int number_of_cylinders;

   //Parameterized constructor
   public Car()
   {
       super("unknown", 0);
       setCylinders(0);
   }

   //Parameterized constructor
   public Car(String name, double maxSpeed,int number_of_cylinders)
   {
       super(name, maxSpeed);
       setCylinders(number_of_cylinders);
   }

   //Set number of cylinders
   public void setCylinders(int number_of_cylinders)
   {
       this.number_of_cylinders=number_of_cylinders;  
   }

   //Returns number of cylinders
   public int getCylinders()
   {
       return number_of_cylinders;  
   }

   //Override the toString method
   @Override
   public String toString()
   {      
       return super.toString()+" Number of Cyliders : "+number_of_cylinders;
   }
}

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

//Airplane.java
//The class Airplane that extends the Vehicle
//that inherits the properties from the vehicle
public class Airplane extends Vehicle
{
   //instance variable
   private int number_of_engines;

   //Parameterized constructor
   public Airplane()
   {
       super("unknown", 0);
       setEngines(0);
   }

   //Parameterized constructor
   public Airplane(String name, double maxSpeed,int number_of_engines)
   {
       super(name, maxSpeed);
       setEngines(number_of_engines);
   }

   //Set number of cylinders
   public void setEngines(int number_of_engines)
   {
       this.number_of_engines=number_of_engines;  
   }

   //Returns number of cylinders
   public int getEngines()
   {
       return number_of_engines;  
   }
   //Override the toString method
   @Override
   public String toString()
   {      
       return super.toString()
               +" Number of Engines : "+number_of_engines;
   }
}

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

//Tester java program
//VehicleDemo.java
public class VehicleDemo
{
   public static void main(String[] args)
   {
      
       //Create an instance of Car
       Car car=new Car();
       car.setName("Benz");
       car.setMaxSpeed(250);
       car.setCylinders(4);
      
       //Create an instance of Airplane
       Airplane airplane=new Airplane();
       airplane.setName("Benz");
       airplane.setMaxSpeed(500);
       airplane.setEngines(5);
      
      
       if(car.getMaxSpeed()>airplane.getMaxSpeed())
           System.out.println("Car speed is more than airplane speed");
       else
           System.out.println("Airplane speed is more than car speed");
      
       System.out.println("Car details");
       System.out.println(car.toString());
      
       System.out.println("Airplane details");
       System.out.println(airplane.toString());
              
   }//end of the main method
}//end of the class

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

Sample Output:

Airplane speed is more than car speed
Car details
Name : Benz Max Speed : 250.0 Number of Cyliders : 4
Airplane details
Name : Benz Max Speed : 500.0 Number of Engines : 5

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