Question

Java language

This is your first homework on objects and classes, and the basics of object-oriented programming. For each exercise, your task is to first write the class that defines the given object. Compile it and check it for syntax errors. Then write the “demo class” with the main program that creates and uses the object.

a)You are planning to purchase a new motor boat for cool cruises on Porter’s Lake this summer, but you want to simulate it before you make the purchase. Write a class MotorBoat that represents motorboats. A motorboat has attributes for

• The capacity of the fuel tank (liters)
• The amount of fuel in the tank (liters)
• The maximum speed of the boat (kmph)
• The current speed of the boat (kmph)
• The rate of fuel consumption (liters/km)
• The distance traveled (km)

and the following methods:

• Constructor that sets the capacity, fuel in the tank, max speed and fuel consumption to the given values and current speed to zero.
• Method to set the current speed of the boat
• Method to get the current speed of the boat
• Method to change the speed of the boat (the method should accept the change which is a positive or negative number and change the current speed. If the change is greater than max speed, it should set the current speed to max speed).
• Operate the boat for an amount of time in minutes at the current speed (this method should set the distance traveled and reduce the amount of fuel in the tank by the appropriate amount).
• Refuel the boat with some amount of fuel (if the total amount of fuel is greater than the capacity, set it to the capacity).
• Return the amount of fuel in the tank
• Return the distance traveled so far

Note: If the rate of fuel consumption is r and the distance traveled is d, then the amount of fuel remaining in the tank = fuel in tank – r*d

b) Write a tester program that creates a motorboat with capacity 100 liters, fuel in tank 50 liters, max. speed 100 kmph, rate of fuel consumption 1. Set its speed to 25 kmph and operate it for 30 minutes. Print the current speed, distance driven and the fuel remaining in the tank. Then increase the speed by 25, and operate it for 30 minutes. Print the current speed, distance driven and fuel in tank. Your output should be:

Current speed: 25.0 kmph

Distance driven: 12.5 km

Fuel in tank: 37.5 liters

Current speed: 50.0 kmph

Distance driven: 25.0 km

Fuel in tank: 12.5 liters

Test your program to check for other cases as well.

Answer 1

JAVA CODE(MotorBoat.java)

class MotorBoat
{
   double fueltank_capacity;
   double fuel_in_tank;
   double max_speed;
   double current_speed;
   double fuel_consumption;
   double distance_travelled;
  
   //constructor to initialize the object
   public MotorBoat(double capacity,double fuel,double maxi_speed,double fuel_consumed)
   {
       fueltank_capacity=capacity;
       fuel_in_tank=fuel;
       max_speed=maxi_speed;
       current_speed=0;
       fuel_consumption=fuel_consumed;
      
   }
  
   // method to get current speed of boat
   public double getCurrent_speed()
   {
      
       return current_speed;
   }
  
  
   // method to set current speed of boat
   public void setCurrent_speed(double speed)
   {
       current_speed=speed;
   }

   // method to change speed of boat
   public void changeSpeed(double speed)
   {
      
       if(speed > max_speed)
       {
           current_speed=max_speed;
       }
       else
       {
           current_speed+=speed;
       }
      
   }
  
   // method to run boat for given minutes
   public void boatRunning(int minutes)
   {
       distance_travelled= current_speed * ((double)minutes/60);
       fuel_in_tank = fuel_in_tank - fuel_consumption * distance_travelled;
   }
  
   // method to refuel the tank
   public void reFuel(double fuel)
   {
       if(fuel > fueltank_capacity)
       {
           fuel_in_tank=fueltank_capacity;
       }
   }
  
   // method to get fuel in tank
   public double fuelInTank()
   {
       return fuel_in_tank;
   }
  
   // method to find distance travelled
   public double distanceTravelled()
   {
       return distance_travelled;
   }
  
}

JAVA CODE (Demo.java)

public class Demo
{
  
   public static void main(String args[])
   {
       // creating MotorBoat object
       MotorBoat ob=new MotorBoat(100,50,100,1);
      
       // change the boat speed
       ob.changeSpeed(25);
      
       // run the boat for 30 minutes
       ob.boatRunning(30);
      
       //displaying speed, distance travelled, fuel in tank
       System.out.printf("Current Speed: %.1f kmph",ob.getCurrent_speed());
       System.out.printf("\nDistance driven: %.1f km",ob.distanceTravelled());
       System.out.printf("\nFuel in tank: %.1f liters",ob.fuelInTank());
      
       // change the boat speed
       ob.changeSpeed(25);
      
       // run the boat for 30 minutes
       ob.boatRunning(30);
      
       //displaying speed, distance travelled, fuel in tank
       System.out.printf("\nCurrent Speed: %.1f kmph",ob.getCurrent_speed());
       System.out.printf("\nDistance driven: %.1f km",ob.distanceTravelled());
       System.out.printf("\nFuel in tank: %.1f liters\n",ob.fuelInTank());
   }
}

SCREENSHOT FOR OUTPUT: