Question

Wolfie's Car Repair Shop For this assignment you will be completing a program that manages cars and car repairs at Wolfie's Car Repair Shop. The program is menu-driven. The menu can be found in Homework.Driver.java. Provided in that file is a series of methods that begin with the prefix main_. Those methods request input from the user and then call methods from the class CarRepairShop. It is these methods in the CarRepairShop that you will be implementing for homework. In essence you will be implementing a very simple database system that uses arrays and possibly a handful of other variables to store data. The methods you write will implement basic "CRUD" functionality, as it is known in the database world: Create, Read, Update and Delete data records. Because a major goal of this assignment is to give you practice working with arrays of objects, you are not permit- ted to use the ArrayList class or any other kind of collection except for arrays. The grading software will ana- lyze your code and search for the use of classes outside the java.lang package. If you import ANY packages or use any fully-qualified class names to use classes outside of java.lang (e.g., java.util.ArrayList), you will receive NO credit for the homework assignment. Methods to Implement Implement the following methods that can be found in CarRepairShop.java. You may create any additional methods and classes you like to complete this homework assignment. Be sure to submit all extra.java files your code needs to compile. Do not submit the driver class. Any files containing a main() method will be deleted when your homework is downloaded for grading. Please note that none of these methods asks the user to give input. Also, none of them produces any output to the screen. 1. int addNewCar(String VIN, String make, int year) (1 point) Adds a new car to the database with the provided VIN, make (e.g., Ford, Honda, Hyundai, etc.) and year of manufacture. If a car with the given VIN already exists in the database, the method returns - 1 and makes no changes to the database. Otherwise, the method returns the number of cars in the database after adding this new car.

Answer 1

Working code implemented in Java and appropriate comments provided for better understanding:

Here I am attaching code for these files:

• CarRepairShop.java
• Ticket.java
• Car.java
• Homework6Driver.java

Source code for CarRepairShop.java:

public class CarRepairShop {
//declaring variables
private int carsCount = 0;
private int tickCount = 0;
private Car[] vehicles = new Car[carsCount + 1];
private Ticket[] tickets = new Ticket[tickCount + 1];

public int addNewCar(String vin, String make, int year) {//we can add car by taking VIN, make and year
int i;
Car[] t = new Car[vehicles.length + 1];
for (i = 0; i<vehicles.length; i++) {
Car car = vehicles[i];
if (car != null) {
t[i] = new Car(car);
}
}
String VIN;
for (i = 0; i<vehicles.length; i++) {
if (vehicles[i] != null) {
VIN = vehicles[i].getVin();
if (VIN.equals(vin)) {
return -1;
}
}
}
t[carsCount] = new Car(vin, make, year);
carsCount++;
vehicles = new Car[carsCount + 1];
for (i = 0; i<vehicles.length; i++) {
Car car = t[i];
if (car != null) {
vehicles[i] = new Car(car);
}
}
return carsCount;
}
public int addRepairTicket(String vin, double cost, String description) {//we can add repairticket by taking vin, cost and description
int i, tempCount = 0;
Ticket[] t = new Ticket[tickets.length + 1];
for (i = 0; i<tickets.length; i++) {
Ticket ticket = tickets[i];
if (ticket != null) {
t[i] = new Ticket(ticket);
}
}
String VIN;
for (i = 0; i<vehicles.length; i++) {
if (vehicles[i] != null) {
VIN = vehicles[i].getVin();
if (VIN.equals(vin)) {
tempCount++;
}
}
}
if (tempCount==0) return -1;
t[tickCount] = new Ticket(vin, cost, description);
tickCount++;
tickets = new Ticket[tickCount + 1];
for (i = 0; i<tickets.length; i++) {
Ticket ticket = t[i];
if (ticket != null) {
tickets[i] = new Ticket(ticket);
}
}
return tickCount;
}
public double getRepairCost(int ticketNum) {//we can get cost of repair using ticket id
if (ticketNum > tickets.length) return -1;
if (ticketNum <= 0) return -1;
if (tickets[ticketNum-1] != null) {
double cost = tickets[ticketNum - 1].getCost();
return cost;
}
else return -1;
}
public double getTotalRepairCosts(String vin) {//we can get total cost of all repairs
int noCarCheck = 0, i;
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[0] == null) {
if (vehicles[i].getVin().equals(vin)) {
noCarCheck++;
}
}
}
if (noCarCheck == 0) return -1;
double cost = 0;
for (i = 0; i<tickets.length - 1; i++) {
if (tickets[i] != null) {
if (tickets[i].getVin().equals(vin)) {
cost += tickets[i].getCost();
}
}
}
return cost;
}

public String getWorstCarMake() { //we can get worst car based on most tickets
int carCheck = 0, i, count = 0, j, tempCount;
String vin, element = "", tempElement, make = "";
String[] ticketArray = new String[tickets.length - 1];
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[i] != null) carCheck++;
}
if (carCheck == 0) return null;
for (i = 0; i<tickets.length - 1; i++) {
if (tickets[i] != null) {
vin = tickets[i].getVin();
ticketArray[i] = vin;
}
}
for (i = 0; i<ticketArray.length; i++) {
tempElement = ticketArray[i];
tempCount = 0;
for (j = 0; j<ticketArray.length; j++) {
if (ticketArray[j].equals(tempElement)) tempCount++;
}
if (tempCount > count) {
element = tempElement;
count = tempCount;
}
}
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[i] != null) {
String VIN = vehicles[i].getVin();
if (VIN.equals(element)) {
make = vehicles[i].getMake();
break;
}
}
}
return make;
}

public boolean updateRepairCost(int ticketNum, double newCost) {//we can update cost of repair using ticket id
if (ticketNum > tickets.length) return false;
if (ticketNum <= 0) return false;
if (tickets[ticketNum - 1] != null) {
tickets[ticketNum - 1].setCost(newCost);
return true;
}
else return false;
}

public boolean deleteRepair(int ticketNum) { //we can delete car using ticket id
if (ticketNum > tickets.length) return false;
if (ticketNum <= 0) return false;
if (tickets[ticketNum - 1] != null) {
tickets[ticketNum - 1] = null;
return true;
}
else return false;
}

public boolean deleteAllRepairsForCar(String VIN) { //we can remove all repairs from car
int noCarCheck = 0, i;
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[0] == null) {
if (vehicles[i].getVin().equals(VIN)) {
noCarCheck++;
}
}
}
if (noCarCheck == 0) return false;
for (i = 0; i<tickets.length - 1; i++) {
if (tickets[i] != null) {
if (tickets[i].getVin().equals(VIN)) {
tickets[i] = null;
}
}
}
return true;
}

public boolean deleteCarAndRepairs(String VIN) { //we can remove car and its repairs
int noCarCheck = 0, i;
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[i] != null) {
if (vehicles[i].getVin().equals(VIN)) {
noCarCheck++;
}
}
}
if (noCarCheck == 0) return false;
for (i = 0; i<vehicles.length - 1; i++) {
if (vehicles[i] != null) {
if (vehicles[i].getVin().equals(VIN)) {
vehicles[i] = null;
}
}
}
for (i = 0; i<tickets.length - 1; i++) {
if (tickets[i] != null) {
if (tickets[i].getVin().equals(VIN)) {
tickets[i] = null;
}
}
}
return true;
}
}

Code Screenshots:

Source code for Ticket.java:

public class Ticket {
//declaring variables
private String vin;
private double cost;
private String description;

public Ticket(String vin, double cost, String description) { //default constructor with parameters
this.vin = vin;
this.cost = cost;
this.description = description;
}

public void setCost(double newCost) { //we can set new cost of ticket
cost = newCost;
}

public String getVin() { //we can get VIN number using this function
return vin;
}

public double getCost() { //we can get cost of ticket
return cost;
}

public String getDescription() { //we can get description of ticket
return description;
}

public Ticket(Ticket ticket) {
this(ticket.getVin(), ticket.getCost(), ticket.getDescription());
}

}

Code Screenshots:

Source code for Car.java:

public class Car { //Car class
//declaring variables
private String vin;
private String make;
private int year;

public Car(String vin, String make, int year) { //default constructor with parameters
this.vin = vin;
this.make = make;
this.year = year;
}

public String getVin() { //we can get vin number of car
return vin;
}

public String getMake() { //we can get make of car
return make;
}

public int getYear() { //we can get year of car released
return year;
}

public Car(Car car) {
this(car.getVin(), car.getMake(), car.getYear());
}
}

Code Screenshots:

Source code for Homework6Driver.java:

import java.util.Scanner;

public class Homework6Driver {

private static Scanner input = new Scanner(System.in);
private static CarRepairShop shop = new CarRepairShop();

public static void main(String[] args) {
int entry;
String[] entries = {
"Add a new car to the database",
"Record repair ticket ID for car",
"Get repair cost by ticket ID",
"Get car's total repair costs using VIN ID",
"Get car having highest total number of repairs",
"Update repair cost by ticket ID",
"Delete a repair ticket by ticket ID",
"Delete all tickets of repairs using VIN ID",
"Delete car and its repairs using VIN ID",
"Exit Program"
};

System.out.println("Welcome to Car Repair Shop!");
do {
System.out.println("\nCar Repair Shop Main Menu");
System.out.println("----------------------------------");
  
for (int i = 0; i < entries.length; i++) {
System.out.println((i < entries.length-1 ? i+1 : 0) + ". " + entries[i]);
}

System.out.print("Make your entry: ");
entry = input.nextInt();

switch (entry) {
case 1: Driver_addNewCar(); //add car to database
break;
case 2: Driver_addRepairTicket(); //generate ticket for repair
break;
case 3: Driver_getRepairCost(); //we can get cost of repair
break;
case 4: Driver_getTotalRepairCosts(); //get cost of total repairs
break;
case 5: Driver_getWorstCarMake(); //gets car with more repairs
break;
case 6: Driver_updateRepairCost(); //update cost of repair
break;
case 7: Driver_deleteRepair(); //remove ticket of repair
break;
case 8: Driver_deleteAllRepairsForCar();// removes all repairs
break;
case 9: Driver_deleteCarAndRepairs();// remove car and its repairs
break;
case 0: System.exit(0); //exit
default:
System.out.println("Invalid entry. Try again.");
}

} while (entry != 0);

input.close();
}

public static void Driver_addNewCar() {
String vin, make;
int year, carNumber;
input.nextLine();
System.out.print("Enter VIN of Car: ");
vin = input.nextLine();
System.out.print("Enter year of Car: ");
year = input.nextInt();
input.nextLine();
System.out.print("Enter make of Car: ");
make = input.nextLine();

carNumber = shop.addNewCar(vin, make, year);
if (carNumber != -1)
System.out.println("Car #" + carNumber + " successfully added.");
else
System.out.println("Error: Entered car was already exists in database.");
}
public static void Driver_addRepairTicket() {
String vin, desc;
int ticketNumber;
double cost;
input.nextLine();
System.out.print("Enter VIN ID of Car: ");
vin = input.nextLine();
System.out.print("Enter the cost of repair: ");
cost = input.nextDouble();
input.nextLine();
System.out.print("Enter the repair description: ");// description problem
desc = input.nextLine();
ticketNumber = shop.addRepairTicket(vin, cost, desc);
if (ticketNumber != -1)
System.out.println("Repair ticket #" + ticketNumber + " successfully added.");
else
System.out.println("Invalid: can't record repair in database.");
}
public static void Driver_getRepairCost() {
int ticketNumber;
double cost;
System.out.print("Enter repair ticket ID: ");
ticketNumber = input.nextInt();
cost = shop.getRepairCost(ticketNumber);
if (cost != -1)
System.out.printf("Repair ticket #" + ticketNumber + " had a cost of $%.2f\n", cost);
else
System.out.println("Invalid ticket number entered.");
}
public static void Driver_getTotalRepairCosts() {
String vin;
double total;
input.nextLine();
System.out.print("Enter VIN: ");
vin = input.nextLine();
total = shop.getTotalRepairCosts(vin);
if (total != -1)
System.out.printf("Total costs to repair car with VIN " + vin + " was $%.2f\n", total);
else
System.out.println("Invalid VIN ID entered");
}
public static void Driver_getWorstCarMake() {
String worstCarMake = shop.getWorstCarMake();
if (worstCarMake == null)
System.out.println("No tickets in database.");
else
System.out.println("The car make with most repairs is: " + worstCarMake);
}

public static void Driver_updateRepairCost() {
int ticketNumber;
boolean success;
double updatedCost;
System.out.print("Enter repair ticket number: ");
ticketNumber = input.nextInt();
System.out.print("Enter new cost of repair: ");
updatedCost = input.nextDouble();
success = shop.updateRepairCost(ticketNumber, updatedCost);
if (success)
System.out.printf("Repair ticket #" + ticketNumber + " updated cost of $%.2f\n", updatedCost);
else
System.out.println("Invalid ticket number entered.");
}
public static void Driver_deleteRepair() {
int ticketNumber;
boolean success;
System.out.print("Enter repair ticket ID: ");
ticketNumber = input.nextInt();
success = shop.deleteRepair(ticketNumber);
if (success)
System.out.println("Repair ticket #" + ticketNumber + " deleted.");
else
System.out.println("Invalid ticket number entered.");
}
public static void Driver_deleteAllRepairsForCar() {
String vin;
boolean success;
input.nextLine();
System.out.print("Enter VIN: ");
vin = input.nextLine();
success = shop.deleteAllRepairsForCar(vin);
if (success)
System.out.println("Deleted repairs for car with VIN " + vin + " from database.");
else
System.out.println("Invalid VIN ID entered.");
}
public static void Driver_deleteCarAndRepairs() {
String vin;
boolean success;
input.nextLine();
System.out.print("Enter VIN ID: ");
vin = input.nextLine();
success = shop.deleteCarAndRepairs(vin);
if (success)
System.out.println("Deleted car with VIN ID" + vin + " from database.");
else
System.out.println("Invalid VIN ID entered.");
}
}

Code Screenshots:

Output Screenshots:

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