Chapter 5, Problem 7E

a.

Method heading for each method:

• • Method heading for change the speed of the boat is “public void changeBoatSpeed(double ns)”.
• • Method heading for time of operate boat is “public void boatOperateTime(double t)”...

b.

Preconditions and postconditions of each method:

• • Precondition and postcondition of “changeBoatSpeed” method.
  • ○ Precondition: The “MotorBoat” class object should be completed and the parameter “ns” is passed to the function which is declared in a double type.
  • ○ Postcondition: The boat current speed is assigned to “ns”.
• • Precondition and postcondition of “boatOperateTime” method.
  • ○ Precondition: The “MotorBoat” class object should be completed and the parameter “t” is passed to the function which is declared in a double type.
  • ○ Postcondition: Amount of fuel is updated by decreasing usage of fuel...

c.

Test class for some Java statement:

//Create object for "MotorBoat" class

MotorBoat boat1 = new MotorBoat();

//Call "setValues" method for object "boat1"

boat1.setValues(5.0, 55.0, 0.001);

//Display given statement

System.out.println("User are trying to travel for 1.0 hour with no fuel.");

//Call "boatOperateTime" method with argument "1".

boat1.boatOperateTime(1.0);

//Display remaining fuel by calling method "computeRemainingFuel"

System.out.println("Fuel left is " + boat1.computeRemainingFuel());

//Display distance travelled by calling method "computeDistanceTraveled"

System.out.println("Distance travelled is " + boat1.computeDistanceTraveled());

//For next line

System.out.println();

//Display given statement

System.out.println("User trying to add 10 gallons of fuel.");

//Display given statement

System.out.println("However they should only be able to hold 5.");

//Call "refuel_Boat" method with argument "10".

boat1.refuel_Boat(10.0);

//Display remaining fuel by calling method "computeRemainingFuel"

System.out.println("Fuel left is " + boat1.computeRemainingFuel());

//Display distance travelled by calling method "computeDistanceTraveled"

System.out.println("Distance travelled is " + boat1.computeDistanceTraveled());

//For next line

System.out.println();

//Display given statement

System.out.println("User are traveling for 1.0 hour with a speed of 0.");

//Call "boatOperateTime" method with argument "1".

boat1.boatOperateTime(1.0);

//Display remaining fuel by calling method "computeRemainingFuel"

System.out.println("Fuel left is " + boat1.computeRemainingFuel());

//Display distance travelled by calling method "computeDistanceTraveled"

System.out.println("Distance travelled is " + boat1.computeDistanceTraveled());

//For next line

System.out.println();     

//Display given statement

System.out.println("User trying to change the speed to 85...

d.

Implementation of class:

MotorBoat.java:

//Import package

import java.util.Scanner;

//Define "MotorBoat" class

public class MotorBoat

{

//Declare required variable in "private" access specifier

    private double fuelTank_capacity;

    private double fuel_In_tank;

    private double maximum_speed;

    private double boat_current_speed;

    private double boat_efficiency;

    private double dist_traveled;

    //Method definition for "setValues"

    public void setValues(double ct, double s, double e)

    {

        //Assign values to given attributes

        fuelTank_capacity = ct;

        fuel_In_tank = 0.0;

        maximum_speed = s;

        boat_current_speed = 0.0;

        boat_efficiency = e;

        dist_traveled = 0.0;

    }

    //Method definition for change boat speed

    public void changeBoatSpeed(double ns)

    {

        //If new speed "ns" is less than "0", then

        if(ns < 0.0)

            //Assign boat current speed to "0"

            boat_current_speed = 0.0;

        //If "ns" is greater than maximum speed, then

        else if (ns > maximum_speed)

//Assign boat current speed to maximum speed

            boat_current_speed = maximum_speed;

        //Otherwise

        else

            //Assign boat current speed to "ns"

            boat_current_speed = ns;

    }

    //Method definition for boat operate time

    public void boatOperateTime(double t)

    {

        //If time "t" is greater than "0", then

        if(t > 0.0 )

        {

            //Compute usage of fuel

double fuelUsage = boat_efficiency * boat_current_speed * boat_current_speed * t;

            //Declare variable for actual time

            double actualTime;

            //Determine if user run out of fuel

            if(fuelUsage > fuel_In_tank)

            {

                //If it is, compute actual time

actualTime = t * (fuel_In_tank/fuelUsage);

                //Assign fuel in tank to "0"

                fuel_In_tank = 0.0;

            }

            //Otherwise

            else

            {

                //Decrement the usage of fuel

                fuel_In_tank -= fuelUsage;

                //Assign actual time to "t"

                actualTime = t;

            }

            //Compute distance travelled

dist_traveled += boat_current_speed * actualTime;

        }

    }

    //Method definition for refuel boat

    public void refuel_Boat(double amt)

    {

        //Check amount of fuel

        if(amt > 0.0)

        {

if (amt + fuel_In_tank > fuelTank_capacity)

                fuel_In_tank = fuelTank_capacity;

            else

                fuel_In_tank += amt;

        }

    }

//Method definition for compute remaining fuel in boat

    public double computeRemainingFuel()

    {

        //Return remaining fuel

        return fuel_In_tank;

    }

    //Method definition for compute distance traveled

    public double computeDistanceTraveled()

    {

        //Return distance traveled

        return dist_traveled;

    }

    //Define main function

    public static void main(String[] args)

    {

        //Create object for "MotorBoat" class

        MotorBoat boat1 = new MotorBoat();

        //Call "setValues" method for object "boat1"

        boat1.setValues(5.0, 55.0, 0.001);

        //Display given statement

System.out.println("User are trying to travel for 1.0 hour with no fuel.");

//Call "boatOperateTime" method with argument "1".

        boat1.boatOperateTime(1.0);

//Display remaining fuel by calling method "computeRemainingFuel"

System.out.println("Fuel left is " + boat1.computeRemainingFuel());

//Display distance travelled by calling method "computeDistanceTraveled"

System.out.println("Distance travelled is " + boat1.computeDistanceTraveled());

        //For next line

        System...