AccountService.java

package banking.service;

import java.sql.*;

public class AccountService {
    private Connection conn;

    public AccountService(Connection conn) {
        this.conn = conn;
    }

    public double getBalance(int accountId) {
        try {
            String sql = "SELECT balance FROM accounts WHERE account_id=?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, accountId);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) return rs.getDouble("balance");
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return 0.0;
    }

    public boolean deposit(int accountId, double amount) {
        try {
            String sql = "UPDATE accounts SET balance = balance + ? WHERE account_id=?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setDouble(1, amount);
            ps.setInt(2, accountId);
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }
}