ExpenseTracker.java

// Expense Tracker Application in Java

import java.util.*;
import java.sql.*;

public class ExpenseTracker {

    private static Connection connection;

    public static void main(String[] args) {
        try {
            connectDatabase();
            createTables();

            Scanner scanner = new Scanner(System.in);
            boolean running = true;

            while (running) {
                System.out.println("\nExpense Tracker Menu:");
                System.out.println("1. Add Expense");
                System.out.println("2. Edit Expense");
                System.out.println("3. Delete Expense");
                System.out.println("4. View Expenses");
                System.out.println("5. Generate Report");
                System.out.println("6. Exit");

                System.out.print("Choose an option: ");
                int choice = scanner.nextInt();
                scanner.nextLine(); // Consume newline

                switch (choice) {
                    case 1:
                        addExpense(scanner);
                        break;
                    case 2:
                        editExpense(scanner);
                        break;
                    case 3:
                        deleteExpense(scanner);
                        break;
                    case 4:
                        viewExpenses();
                        break;
                    case 5:
                        generateReport();
                        break;
                    case 6:
                        running = false;
                        break;
                    default:
                        System.out.println("Invalid option. Please try again.");
                }
            }

            scanner.close();
            closeDatabase();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void connectDatabase() throws SQLException {
        String url = "jdbc:sqlite:expenses.db";
        connection = DriverManager.getConnection(url);
        System.out.println("Connected to the database.");
    }

    private static void createTables() throws SQLException {
        String createTableSQL = "CREATE TABLE IF NOT EXISTS expenses (" +
                "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
                "amount REAL, " +
                "category TEXT, " +
                "date TEXT, " +
                "description TEXT)";

        Statement stmt = connection.createStatement();
        stmt.execute(createTableSQL);
        stmt.close();
    }

    private static void addExpense(Scanner scanner) throws SQLException {
        System.out.print("Enter amount: ");
        double amount = scanner.nextDouble();
        scanner.nextLine(); // Consume newline

        System.out.print("Enter category: ");
        String category = scanner.nextLine();

        System.out.print("Enter date (YYYY-MM-DD): ");
        String date = scanner.nextLine();

        System.out.print("Enter description: ");
        String description = scanner.nextLine();

        String insertSQL = "INSERT INTO expenses (amount, category, date, description) VALUES (?, ?, ?, ?)";
        PreparedStatement pstmt = connection.prepareStatement(insertSQL);
        pstmt.setDouble(1, amount);
        pstmt.setString(2, category);
        pstmt.setString(3, date);
        pstmt.setString(4, description);
        pstmt.executeUpdate();
        pstmt.close();

        System.out.println("Expense added successfully.");
    }

    private static void editExpense(Scanner scanner) throws SQLException {
        System.out.print("Enter expense ID to edit: ");
        int id = scanner.nextInt();
        scanner.nextLine(); // Consume newline

        System.out.print("Enter new amount: ");
        double amount = scanner.nextDouble();
        scanner.nextLine();

        System.out.print("Enter new category: ");
        String category = scanner.nextLine();

        System.out.print("Enter new date (YYYY-MM-DD): ");
        String date = scanner.nextLine();

        System.out.print("Enter new description: ");
        String description = scanner.nextLine();

        String updateSQL = "UPDATE expenses SET amount = ?, category = ?, date = ?, description = ? WHERE id = ?";
        PreparedStatement pstmt = connection.prepareStatement(updateSQL);
        pstmt.setDouble(1, amount);
        pstmt.setString(2, category);
        pstmt.setString(3, date);
        pstmt.setString(4, description);
        pstmt.setInt(5, id);
        pstmt.executeUpdate();
        pstmt.close();

        System.out.println("Expense updated successfully.");
    }

    private static void deleteExpense(Scanner scanner) throws SQLException {
        System.out.print("Enter expense ID to delete: ");
        int id = scanner.nextInt();

        String deleteSQL = "DELETE FROM expenses WHERE id = ?";
        PreparedStatement pstmt = connection.prepareStatement(deleteSQL);
        pstmt.setInt(1, id);
        pstmt.executeUpdate();
        pstmt.close();

        System.out.println("Expense deleted successfully.");
    }

    private static void viewExpenses() throws SQLException {
        String selectSQL = "SELECT * FROM expenses";
        Statement stmt = connection.createStatement();
        ResultSet rs = stmt.executeQuery(selectSQL);

        System.out.println("\nExpenses:");
        System.out.println("ID | Amount | Category | Date | Description");
        while (rs.next()) {
            System.out.printf("%d | %.2f | %s | %s | %s\n",
                    rs.getInt("id"),
                    rs.getDouble("amount"),
                    rs.getString("category"),
                    rs.getString("date"),
                    rs.getString("description"));
        }

        rs.close();
        stmt.close();
    }

    private static void generateReport() throws SQLException {
        String reportSQL = "SELECT category, SUM(amount) AS total FROM expenses GROUP BY category";
        Statement stmt = connection.createStatement();
        ResultSet rs = stmt.executeQuery(reportSQL);

        System.out.println("\nExpense Report by Category:");
        while (rs.next()) {
            System.out.printf("%s: %.2f\n", rs.getString("category"), rs.getDouble("total"));
        }

        rs.close();
        stmt.close();
    }

    private static void closeDatabase() throws SQLException {
        if (connection != null) {
            connection.close();
            System.out.println("Database connection closed.");
        }
    }
}