public class DataBase {
    Connection connection;
    Statement statement;
    PreparedStatement preparedStatement;
    ResultSet result;


    public DataBase() throws SQLException {
        connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/rentalcar?autoReconnect=true&serverTimezone=" + TimeZone.getDefault().getID(), "...", "...");
        statement = connection.createStatement();
    }

   ...

    public void insertNewCar(String brand, String productionYear, String engineCapacity, int dayPrice, String avaible) throws SQLException {
        String sql = "insert into car" + "(brand, productionYear, engineCapacity,dayPrice,avaible)" + "values(?,?,?,?,?)";
        preparedStatement.setString(1, brand);
        preparedStatement.setString(2, productionYear);
        preparedStatement.setString(3, engineCapacity);
        preparedStatement.setInt(4, dayPrice);
        preparedStatement.setString(5, avaible);
        preparedStatement.executeUpdate(sql);
    }