/* POS_and_Inventory.java
* Written By Dr. Jake Rodriguez Pomperada, MAED-IT, MT, PhD.-TM
* Tools : Java SE, MySQL and MySQL Connector for Java, Eclipse IDE
* Date : February 4, 2026 Wednesday
* Location : Bacolod City, Negros Occidental Philippines
*/
package demo;
import java.sql.*;
import java.util.Scanner;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class POS_and_Inventory {
static final String URL = "jdbc:mysql://localhost:3306/pos_db";
static final String USER = "root";
static final String PASS = "";
static final double VAT = 0.12;
static Scanner sc = new Scanner(System.in);
public static void main(String[] args) {
try (Connection con = DriverManager.getConnection(URL, USER, PASS)) {
while (true) {
showTitle();
showMenu();
System.out.print("Select Option: ");
int choice = sc.nextInt();
switch (choice) {
case 1 -> addProduct(con);
case 2 -> viewProducts(con);
case 3 -> updateStock(con);
case 4 -> sellProduct(con);
case 5 -> {
System.out.println("Thank you for using POS System!");
System.exit(0);
}
default -> System.out.println("Invalid choice!");
}
System.out.println("\nPress Enter to continue...");
sc.nextLine();
sc.nextLine();
}
} catch (Exception e) {
e.printStackTrace();
}
}
// ================= TITLE =================
static void showTitle() {
System.out.println("\n===========================================");
System.out.println(" POINT OF SALE SYSTEM IN JAVA AND MYSQL");
System.out.println("===========================================");
}
// ================= MENU =================
static void showMenu() {
System.out.println("1. Add Product");
System.out.println("2. View Inventory");
System.out.println("3. Update Stock");
System.out.println("4. Sell Product (POS)");
System.out.println("5. Exit");
System.out.println("-------------------------------------------");
}
// ================= ADD PRODUCT =================
static void addProduct(Connection con) throws Exception {
sc.nextLine();
System.out.print("Product Name : ");
String name = sc.nextLine();
System.out.print("Price : ");
double price = sc.nextDouble();
System.out.print("Quantity : ");
int qty = sc.nextInt();
PreparedStatement ps = con.prepareStatement(
"INSERT INTO products(name,price,qty) VALUES(?,?,?)");
ps.setString(1, name);
ps.setDouble(2, price);
ps.setInt(3, qty);
ps.executeUpdate();
System.out.println("Product successfully added!");
}
// ================= VIEW PRODUCTS =================
static void viewProducts(Connection con) throws Exception {
ResultSet rs = con.createStatement()
.executeQuery("SELECT id,name,price,qty FROM products");
System.out.println("\nID NAME PRICE QTY");
System.out.println("----------------------------------");
while (rs.next()) {
System.out.printf("%-3d %-10s %-9.2f %-5d%n",
rs.getInt("id"),
rs.getString("name"),
rs.getDouble("price"),
rs.getInt("qty"));
}
}
// ================= SHOW PRODUCTS FOR SELLING =================
static void showProductsForSelling(Connection con) throws Exception {
ResultSet rs = con.createStatement()
.executeQuery("SELECT id,name,price,qty FROM products");
System.out.println("\nAVAILABLE PRODUCTS");
System.out.println("ID NAME PRICE STOCK");
System.out.println("--------------------------------");
while (rs.next()) {
System.out.printf("%-4d %-10s %-9.2f %-5d%n",
rs.getInt("id"),
rs.getString("name"),
rs.getDouble("price"),
rs.getInt("qty"));
}
}
// ================= UPDATE STOCK =================
static void updateStock(Connection con) throws Exception {
showProductsForSelling(con);
System.out.print("Product ID : ");
int id = sc.nextInt();
PreparedStatement psSelect = con.prepareStatement(
"SELECT name, qty FROM products WHERE id=?");
psSelect.setInt(1, id);
ResultSet rs = psSelect.executeQuery();
if (!rs.next()) {
System.out.println("Product not found!");
return;
}
System.out.println("\nSelected Product : " + rs.getString("name"));
System.out.println("Current Stock : " + rs.getInt("qty"));
System.out.print("New Stock : ");
int newQty = sc.nextInt();
System.out.print("Confirm update? (Y/N): ");
char confirm = sc.next().toUpperCase().charAt(0);
if (confirm != 'Y') {
System.out.println("Update cancelled.");
return;
}
PreparedStatement psUpdate = con.prepareStatement(
"UPDATE products SET qty=? WHERE id=?");
psUpdate.setInt(1, newQty);
psUpdate.setInt(2, id);
psUpdate.executeUpdate();
System.out.println("Stock updated successfully!");
}
// ================= POS / SELL PRODUCT =================
static void sellProduct(Connection con) throws Exception {
double grandSubtotal = 0;
int totalItemsPurchased = 0;
boolean moreItems = true;
String[] items = new String[50];
int[] qtys = new int[50];
double[] totals = new double[50];
int count = 0;
LocalDateTime now = LocalDateTime.now();
DateTimeFormatter dtf =
DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
DateTimeFormatter receiptFmt =
DateTimeFormatter.ofPattern("yyyyMMdd-HHmmss");
String receiptNo = "OR-" + now.format(receiptFmt);
while (moreItems) {
showProductsForSelling(con);
System.out.print("Product ID : ");
int id = sc.nextInt();
PreparedStatement ps = con.prepareStatement(
"SELECT * FROM products WHERE id=?");
ps.setInt(1, id);
ResultSet rs = ps.executeQuery();
if (!rs.next()) {
System.out.println("Invalid product!");
continue;
}
String productName = rs.getString("name");
double price = rs.getDouble("price");
int stock = rs.getInt("qty");
System.out.println("Selected Product : " + productName);
System.out.print("Quantity : ");
int qty = sc.nextInt();
if (qty <= 0 || qty > stock) {
System.out.println("Invalid quantity!");
continue;
}
double lineTotal = price * qty;
grandSubtotal += lineTotal;
totalItemsPurchased += qty;
// store item
items[count] = productName;
qtys[count] = qty;
totals[count] = lineTotal;
count++;
PreparedStatement upd = con.prepareStatement(
"UPDATE products SET qty = qty - ? WHERE id=?");
upd.setInt(1, qty);
upd.setInt(2, id);
upd.executeUpdate();
double runningVat = grandSubtotal * VAT;
double runningTotalToPay = grandSubtotal + runningVat;
// ===== DISPLAY PREVIOUS + NEW PURCHASES =====
System.out.println("\nCURRENT TRANSACTION ITEMS");
for (int i = 0; i < count; i++) {
System.out.printf("%d. %s x%d = Php %.2f%n",
(i + 1), items[i], qtys[i], totals[i]);
}
System.out.println("--------------------------------");
System.out.printf(
"Running Amount to Pay (with VAT): Php %.2f%n",
runningTotalToPay);
System.out.print("\nAdd another item? (Y/N): ");
moreItems = sc.next().equalsIgnoreCase("Y");
}
double vatAmount = grandSubtotal * VAT;
double total = grandSubtotal + vatAmount;
double cash;
do {
System.out.printf("\nTOTAL AMOUNT TO PAY : Php %.2f%n", total);
System.out.print("Cash Tendered : ");
cash = sc.nextDouble();
} while (cash < total);
double change = cash - total;
// ================= OFFICIAL RECEIPT =================
System.out.println("\n==========================================================");
System.out.println(" POINT OF SALE SYSTEM IN JAVA AND MYSQL");
System.out.println(" Created By Dr. Jake Rodriguez Pomperada, PhD.");
System.out.println(" THIS SERVES AS THE OFFICIAL RECEIPT");
System.out.println("==========================================================");
System.out.println("Receipt No : " + receiptNo);
System.out.println("Date/Time : " + now.format(dtf));
System.out.println("Items Sold : " + totalItemsPurchased);
System.out.println("------------------------------------");
for (int i = 0; i < count; i++) {
System.out.printf("%d. %s x%d = Php %.2f%n",
(i + 1), items[i], qtys[i], totals[i]);
}
System.out.println("------------------------------------");
System.out.printf("SUBTOTAL : Php %.2f%n", grandSubtotal);
System.out.printf("VAT (12%%): Php %.2f%n", vatAmount);
System.out.printf("TOTAL : Php %.2f%n", total);
System.out.printf("CASH : Php %.2f%n", cash);
System.out.printf("CHANGE : Php %.2f%n", change);
System.out.println("====================================");
}
}
