public class App {

private static String dbName;
private static String userName;
private static String password;

public static void connect() throws IOException {
    BufferedReader br = new BufferedReader(new FileReader("login.txt"));

    dbName = br.readLine();
    userName = br.readLine();
    password = br.readLine();

    Connection c = null;
    try {
        Class.forName("org.postgresql.Driver");
        c = DriverManager.getConnection(dbName, userName, password);
    } catch (Exception e) {
        e.printStackTrace();
        System.err.println(e.getClass().getName() + ": " + e.getMessage());
        System.exit(0);
    }
    System.out.println("Opened database successfully");
}

public static void query() {

    Connection c = connect();   // call function - mistake
    Statement stmt = c.createStatement();
    stmt = c.createStatement();
    String query = "Select count(distinct country) sum from customers";
    ResultSet rs = stmt.executeQuery(query);
    query = "SELECT C.country, SUM(O.netamount) netamount" + "from customers as C join orders as O "
            + "on C.customerid = O.customerid " + "where O.orderdate < '20040701' and O.orderdate > '20031231' "
            + "group by C.country " + "order by SUM(O.netamount) DESC";
    rs = stmt.executeQuery(query);
    while (rs.next()) {
        String country = rs.getString("country");
        String netamount = rs.getString("netamount");
        System.out.println(country + " " + netamount);
        System.out.println();
    }
    rs.close();
    stmt.close();
    c.close();
}

public static void main(String[] args) {

    query();  // call function
}