Question

Java Programming --- complete the given classes

DeLand Space Car Dealer needs a new program for their inventory management system. The program needs the following classes:

• A main class (SpaceCarDealer.java) that includes the main method and GUI.

Two instantiable classes:

• CarDealer.java

o Variables to store the dealer name, and the carsOnLot array in Car type. o A constructor to initialize the name variable with the given dealer name. o An accessor method to return the name of the dealer.

o An accessor method to return the cars on lot.

o A mutator method to buy a car and add to the car dealer inventory.

o A mutator method to sell the car with the given sale price and remove the car from dealer’s inventory.

o A mutator method that makes the necessary changes to update the sale price of the car.

• Car.java

o Variables to store makeAndModel, purchasePrice, and salePrice. o A constructor to initialize the variables with the given parameters. o An accessor method to return the purchase price.

o A mutator method to update the sale price with the given new price.

SpaceCarDealer.java

import javax.swing.JOptionPane;
public class SpaceCarDealer {
public static void main(String[] args) {
String input;
int response = 0;
double newPrice;
Car selectedCar;
CarDealer delandCarDealer = new CarDealer("DeLand", 20);
String[] option = {
"Exit",
"Sell",
"Buy",
"UpdatePrice"
};
do {
response = JOptionPane.showOptionDialog(null,
delandCarDealer.getCarsOnLot(),
"DeLand Car Dealer",
0,
JOptionPane.INFORMATION_MESSAGE,
null,
option,
option[2]);
switch (response) {
case 0:
break;
case 1:
selectedCar = (Car) JOptionPane.showInputDialog(null,
"Select: ",
"Pick Car to Sell: ",
JOptionPane.QUESTION_MESSAGE,
null,
delandCarDealer.getCarsOnLot(),
delandCarDealer.getCarsOnLot()[0]
);
delandCarDealer.sellACar(selectedCar);
break;
case 2:
input = JOptionPane.showInputDialog(null, "Make and Model:
");

newPrice =
Double.parseDouble(JOptionPane.showInputDialog("Purchase Price: "));
//sale price with 20 percent profit: newPrice*1.2
delandCarDealer.buyACar(new Car(input, newPrice,
newPrice * 1.2));
break;
case 3:
selectedCar = (Car) JOptionPane.showInputDialog(null,
"Select: ",
"Update the sale price",
JOptionPane.QUESTION_MESSAGE,
null,
delandCarDealer.getCarsOnLot(),
delandCarDealer.getCarsOnLot()[0]
); newPrice =

Double.parseDouble(JOptionPane.showInputDialog("Purchase Price: ")); delandCarDealer.UpdateSalePrice(selectedCar, newPrice);
break;
}
}
while (response != 0);
}

}

CarDealer.java

import java.util.Arrays;
public class CarDealer {
private String dealerName;
private Car[] carsOnLot;
public CarDealer(String dealerName, int num) {
this.dealerName = dealerName;
this.carsOnLot = new Car[num];
}
@Override
public String toString() {
return "CarDealer [dealerName=" + dealerName + ", carsOnLot=" +
Arrays.toString(carsOnLot) + "]";
}
}

Car.java

public class Car {
private String makeAndModel;
private double purchasePrice;
private double salePrice;
public Car() {
this.makeAndModel = null;
this.purchasePrice = 0;
this.salePrice = 0;
}
@Override
public String toString() {
return String.format("%20s $%12.2f", makeAndModel, salePrice);
}

}

Answer 1

Hello,

Below is the code required for above problem :

There are no changes in the SpaceCarDealer class. It's the same as before. I have made the changes that are required in the CarDealer and Car class. I have also added comments that you can reference for better understanding.

SpaceCarDealer.java :

import javax.swing.JOptionPane;
public class SpaceCarDealer {
    public static void main(String[] args) {
        String input;
        int response = 0;
        double newPrice;
        Car selectedCar;
        CarDealer delandCarDealer = new CarDealer("DeLand", 20);
        String[] option = {
                "Exit",
                "Sell",
                "Buy",
                "UpdatePrice"
        };
        do {
            response = JOptionPane.showOptionDialog(null,
                    delandCarDealer.getCarsOnLot(),
                    "DeLand Car Dealer",
                    0,
                    JOptionPane.INFORMATION_MESSAGE,
                    null,
                    option,
                    option[2]);
            switch (response) {
                case 0:
                    break;
                case 1:
                    selectedCar = (Car) JOptionPane.showInputDialog(null,
                            "Select: ",
                            "Pick Car to Sell: ",
                            JOptionPane.QUESTION_MESSAGE,
                            null,
                            delandCarDealer.getCarsOnLot(),
                            delandCarDealer.getCarsOnLot()[0]
                    );
                    delandCarDealer.sellACar(selectedCar);
                    JOptionPane.showMessageDialog(null,"Buying Price :  "+
                    selectedCar.getPurchasePrice()+"\nSelling Price : " + selectedCar.getPurchasePrice()*1.2+
                    "\nProfit : " +(selectedCar.getPurchasePrice()*1.2 - selectedCar.getPurchasePrice()));
                    break;
                case 2:
                    input = JOptionPane.showInputDialog(null, "Make and Model:");
                    newPrice =Double.parseDouble(JOptionPane.showInputDialog("Purchase Price: "));
                    //sale price with 20 percent profit: newPrice*1.2
                    delandCarDealer.buyACar(new Car(input, newPrice,newPrice * 1.2));
                    break;
                case 3:
                    selectedCar = (Car) JOptionPane.showInputDialog(null,
                            "Select: ",
                            "Update the sale price",
                            JOptionPane.QUESTION_MESSAGE,
                            null,
                            delandCarDealer.getCarsOnLot(),
                            delandCarDealer.getCarsOnLot()[0]
                    );
                    newPrice = Double.parseDouble(JOptionPane.showInputDialog("Purchase Price: ")); delandCarDealer.updateSalePrice(selectedCar, newPrice);
                    break;
            }
        }
        while (response != 0);
    }

}

CarDealer.java :

import java.util.Arrays;
public class CarDealer {
    //instance variables for the class CarDealer
    private String dealerName;
    private Car[] carsOnLot;

    //Parameterized constructor to create a CarDealer object
    public CarDealer(String dealerName, int num) {
        this.dealerName = dealerName;
        this.carsOnLot = new Car[num];
    }
    //Overriding toString method to provide our own implementation of the method
    @Override
    public String toString() {
        return "CarDealer [dealerName=" + dealerName + ", carsOnLot=" +
                Arrays.toString(carsOnLot) + "]";
    }

    //Accessor method to return the array carsOnLot
    public Car[] getCarsOnLot() {
        return carsOnLot;
    }

    //method to sellACar. What we are doing is we are running an array from 0 to the length of the carsOnLot array.
    //After that we get the currentCar from the array, and compare it to the car that we want to sell. If it matches,
    //we delete that car from the array by shifting each car present in the array to one position backwards.
    public void sellACar(Car selectedCar) {
        for(int i=0;i<carsOnLot.length;i++){
            Car car = carsOnLot[i];
            if(selectedCar==car){
                for(int j=i;j<carsOnLot.length - 1; j++){
                    carsOnLot[j] = carsOnLot[j+1];
                }
                break;
            }
        }
    }

    //method to buyACar, what we are doing is we are running the loop from 1 to the length of the array. After that we
    //are checking for the position which is null, that is where there is no car object present, and in that position
    //we are assiging our car object and adding our car object to the inventory.
    public void buyACar(Car car) {
        for(int i=0;i<carsOnLot.length;i++){
            Car currentCar = carsOnLot[i];
            if(null == currentCar){
                carsOnLot[i]=car;
                break;
            }
        }
    }

    //method to updateSalePrice of the car. We are running a loop on the carsOnLot array and getting the current car on the position i
    //If it matches the car provided whose sale price we want to update, we call the setSalePrice method of Car object on that car.
    public void updateSalePrice(Car selectedCar, double newPrice) {
        for(int i=0; i< carsOnLot.length;i++){
            Car car = carsOnLot[i];
            if(selectedCar==car){
                selectedCar.setSalePrice(newPrice);
                break;
            }
        }
    }
}

Car.java :

public class Car {
    private String makeAndModel;
    private double purchasePrice;
    private double salePrice;

    //default constructor.
    public Car() {
        this.makeAndModel = null;
        this.purchasePrice = 0;
        this.salePrice = 0;
    }

    //parameterized constructor to create a car object provided on user information
    public Car(String makeAndModel,double purchasePrice, double salePrice) {
        this.makeAndModel = makeAndModel;
        this.purchasePrice = purchasePrice;
        this.salePrice = salePrice;
    }
    @Override
    public String toString() {
        return String.format("%20s $%12.2f", makeAndModel, salePrice);
    }

    //method to set the sale price
    public void setSalePrice(double salePrice){
        this.salePrice = salePrice;
    }

    //method to get the purchase price
    public double getPurchasePrice(){
        return purchasePrice;
    }
}

Sample Output :

DeLand Car Dealer Exit S ell B uy UpdatePrice

Buying a car :

Input Make and Model: ABC OK Cancel

Input Purchase Price: 80 OK Cancel

Deland Car Dealer 96.00 ABC $ Sell Exit B uy UpdatePrice

Updating price :

Update the sale price Select: ABC $ 96.00 OK Cancel

Input Purchase Price: OK Cancel

DeLand Car Dealer ABC $ 60.00 Exit Sell B uy UpdatePrice

Selling A Car :

Pick Car to Sell: Select: ABC $ 60.00 OK Cancel

Sample Output of Profit :

DeLand Car Dealer ABC $ 108.00 Exit Sell B uy UpdatePrice

Pick Car to Sell: Select ABC $ 108.00 OK Cancel

Message Buying Price: 90.0 Selling Price: 108.0 Profit: 18.0 Tok|

DeLand Car Dealer Exit S ell B uy UpdatePrice

Input Make and Model: ABC OK Cancel

Input Purchase Price: 80 OK Cancel

Deland Car Dealer 96.00 ABC $ Sell Exit B uy UpdatePrice

Update the sale price Select: ABC $ 96.00 OK Cancel

Input Purchase Price: OK Cancel

DeLand Car Dealer ABC $ 60.00 Exit Sell B uy UpdatePrice

Pick Car to Sell: Select: ABC $ 60.00 OK Cancel

DeLand Car Dealer Exit S ell B uy UpdatePrice

Input Make and Model: ABC OK Cancel

Input Purchase Price: 80 OK Cancel

Deland Car Dealer 96.00 ABC $ Sell Exit B uy UpdatePrice

Update the sale price Select: ABC $ 96.00 OK Cancel

Input Purchase Price: OK Cancel

DeLand Car Dealer ABC $ 60.00 Exit Sell B uy UpdatePrice

Pick Car to Sell: Select: ABC $ 60.00 OK Cancel