POS_System.java

import java.io.*;
import java.util.Scanner;

class Item implements Serializable{
    private String itemCode;
    private double price;
    private String size;
    private String product;

    public Item(String cd){
        try {
            String filepath = "products.csv";
            FileReader filereader = new FileReader(filepath);
            BufferedReader bufferedreader = new BufferedReader(filereader);
            bufferedreader.readLine();
            String line;
            while((line = bufferedreader.readLine())!= null){
                String[] det = line.split(",");

                if(det[0].equals(cd)){
                    this.itemCode = det[0];
                    this.price = Double.parseDouble(det[1]);
                    this.size = det[2];
                    this.product = det[6];
                    break;
                }    
            }
        } catch (IOException e) {
            System.out.println("Error Finding File.");
        }
        
    }

    public String getItemName(){
        return this.product;
    }

    public double getUnitPrice(){
        return this.price;
    }
}

class Bill implements Serializable{
    private int billNo;
    private String cashier;
    private String branch;
    private String customer;
    private Item[] items;
    private int[] quantity;
    private double tot_price;
    private int count;

    public Bill(int num, String branch, String cashier){
        this.billNo = num;
        this.count = 0;
        this.items = new Item[10];
        this.quantity = new int[10];

        Scanner scanner1 = new Scanner(System.in);
        this.cashier =  cashier;

        this.branch = branch;

        System.out.print("Customer Name: ");
        this.customer = scanner1.nextLine();
        String cd;
        
        while(true){
            System.out.print("Item Code: ");
            cd = scanner1.nextLine();
            if(cd.equals("-1")){
                break;
            }
            else if(cd.equals("-2")){
                this.serialize();
            }
            else{
                inputItems(cd);
                
            }
        }
    }

    public void inputItems(String cd){
        Item item = new Item(cd);
        this.items[count] = item;
        
        Scanner scanner2 = new Scanner(System.in);
        System.out.print("Quantity: ");
        this.quantity[count] = scanner2.nextInt();
        
        count++;
    }

    public void serialize(){
        try {
            FileOutputStream file = new FileOutputStream("bills.txt");
            ObjectOutputStream oos = new ObjectOutputStream(file);

            oos.writeObject(this);
            oos.close();
            file.close();
            System.out.println("Bill has been saved.");

        } catch (Exception e) {
            System.out.println("Error Serializing...");
        }
        
    }

    public void printBill() {
        System.out.println("=========================================");
        System.out.printf("Cashier : %s\n", this.cashier);
        System.out.printf("Branch  : %s\n", this.branch);
        System.out.printf("Customer: %s\n", this.customer);
        System.out.println("-----------------------------------------");
        System.out.printf("%-15s %-10s %-12s %-10s\n", "Item", "Quantity", "Unit Price", "Total");
        System.out.println("-----------------------------------------");
    
        int i = 0;
        this.tot_price = 0; // reset before calculating
        while (items[i] != null) {
            String name = items[i].getItemName();
            int qn = quantity[i];
            double unit_p = items[i].getUnitPrice();
            double tot_p = (unit_p * qn);
            this.tot_price += tot_p;
    
            System.out.printf("%-15s %-10d %-12.2f %-10.2f\n", name, qn, unit_p, tot_p);
            i++;
        }
    
        System.out.println("-----------------------------------------");
        System.out.printf("%-39s %-10.2f\n", "TOTAL:", this.tot_price);
        System.out.println("=========================================");
        System.out.println("          THANK YOU - COME AGAIN!         ");
        System.out.println("=========================================");
    }
    
}

public class POS_System{
    public static void main(String[] args){
        Scanner scanner3 = new Scanner(System.in);

        System.out.print("Input Cashier Name: ");
        String cashier_name = scanner3.nextLine();

        System.out.print("Input Branch Name: ");
        String branch = scanner3.nextLine();
        int billNo = 0;
        System.out.print("0 - New Bill, 1 - Deserialize Bill: ");
        int resp = scanner3.nextInt();
        if (resp == 0){
            Bill bill = new Bill(billNo, branch, cashier_name);
            System.out.println("\n");
            bill.printBill();
        }
        else if(resp == 1){
            try {
                FileInputStream file = new FileInputStream("bills.txt");
                ObjectInputStream ois = new ObjectInputStream(file);
                Bill bill = (Bill) ois.readObject();
                ois.close();
                file.close();
                bill.printBill();

            } catch (Exception e) {
                System.out.println("File Not Found.");
            }
        }
        
    }
}