Question

Diego’s Bike Lab Lab Objectives • Be able to create both default and non-default constructors • Be able to create accessor and mutator methods • Be able to create toString methods • Be able to refer to both global and local variables with the same name Introduction Until now, you have just simply been able to refer to any variable by its name. This works for our purposes, but what happens when there are multiple variables with the same name? In this lab, you will be learning how to refer to both global and local variables, as well as where you can access them.

Task #1 – Creating the Constuctor 1. Create a constructor for the Bike class • A default constructor is a constructor with no parameters, that is used to set up an object with default values • A non-default constructor is a constructor that uses parameters to set up an object with specific values

Task #2 Calculating the Cost 2. Create a method that calculates the cost of the Bike object • To find the cost, use the following formula cost = numGears × topSpeed • Return the value of cost to where the method was called (the constructor) by typing the return keyword and providing it with a value

package bikeshop; import java.util.Random; /** * BikeShop Lab * * @author Diego Vera */ public class BikeShopDriver { public static void main(String[] args) { Bike bike1 = new Bike(8, 30); Bike bike2 = new Bike(7, 35); Random rand = new Random(); //Task 3b: Use the "ride" method that you just created to increase the distance //travelled on each bike by a random amount, from 5 to 20, inclusive //HINT: use rand.nextInt(n) to get a random number from 0 to n. //Task 4b: Use the .toString method to print the attributes of the bike //that travelled the furthest distance. //Task 5: Use the .toString method to print the attributes of the bike //with the highest cost. //HINT: You may need to create a method of some sort to be able to //access some variables } }

package bikeshop; /** * * @author Diego Vera */ public class Bike { public final int numWheels = 2; //The final keyword means that once the variable //is set, it can never be changed public int numGears; //Between 7-11 gears public double topSpeed; //Between 20-40 mph private double distance; //Task 1: Create both the default and non-default constructor //Both constructors should initialize all global variables //Task 1a: Create the default constructor public Bike() { //This should create a generic Bike that can still be used } //Task 1b: Create the non-default constructor without changing the name of //any parameters //HINT: Use the this keyword to refer to global variables by typing //this.yourVariableName //SECOND HINT: Try using cost = calculateCost(); to set the value of cost to //the value returned in the calculateCost method public Bike(int numGears, double topSpeed) { } //Task 2: Create a method to calculate the cost of a bike, where the cost is //equal to numGears * topSpeed private double calculateCost() { } //Task 3a: Create a method that increases the distance traveled by a given amount public void ride(int distance){ } //Task 4a: Create a .toString method that prints out each bike object's attributes public String toString() { } }

Need help completing this program.

Answer 1

//BikeShopDriver.java

import java.util.Random;
public class BikeShopDriver
{
   public static void main(String[] args)
   {

   double cost;
   Bike bike1 = new Bike(8, 30);
   Bike bike2 = new Bike(7, 35);
   Bike bike3 = new Bike();
   Random rand = new Random();
   int ridedist=rand.nextInt(20 - 5 + 1) + 5;
   System.out.println("Byke1 Cost :"+bike1.calculateCost());
   bike1.toString1();           //Display Byke1 Attributes
   System.out.println("Byke2 Cost :"+bike2.calculateCost());
   bike2.toString1();           //Display Byke2 Attributes
  
   System.out.println("Byke2 Cost :"+bike3.calculateCost());
   bike3.toString1();           //Display Byke3 Attributes

   }
}

class Bike
{
   public final int numWheels = 2;           //The final keyword means that once the variable    //is set, it can never be changed
   public int numGears;               //Between 7-11 gears
   public double topSpeed;               //Between 20-40 mph
   private double distance =40;
   public double cost;
  
       //This should create a generic Bike that can still be used
   public Bike()      
   {
       numGears=7;       //default taken 7 gears
       topSpeed=20;       //default taken 20 kmph
      
       cost= numGears * topSpeed;
              
   }
   //Parameterized constructor
   public Bike(int Gears,double Speed)          
   {
       this.numGears=Gears;      
       this.topSpeed=Speed;      
              
       cost= numGears * topSpeed;
              
   }
   //Task 2: Create a method to calculate the cost of a bike, where the cost is
   public double calculateCost()
   {
       return cost;
   }

   //Task 3a: Create a method that increases the distance traveled by a given amount
   public void ride(int d)
   {
       distance=distance+d;
   }

   //Task 4a: Create a .toString method that prints out each bike object's attributes
   public void toString1()
   {
   System.out.println("bike object's attributes :");
   System.out.println("numGears :"+numGears);
   System.out.println("numWheels :"+numWheels);
   System.out.println("topSpeed :"+topSpeed);
   System.out.println("distance :"+distance);
   System.out.println("cost :"+cost);
   }

}

Output:

javac BikeShopDriver.java
$java -Xmx128M -Xms16M BikeShopDriver
Byke1 Cost :240.0
bike object's attributes :
numGears :8
numWheels :2
topSpeed :30.0
distance :40.0
cost :240.0
Byke2 Cost :245.0
bike object's attributes :
numGears :7
numWheels :2
topSpeed :35.0
distance :40.0
cost :245.0
Byke2 Cost :140.0
bike object's attributes :
numGears :7
numWheels :2
topSpeed :20.0
distance :40.0
cost :140.0