Connection connection_db(String username, String password, String dbname, Connection c) {
    try {
        Class.forName("org.postgresql.Driver");
        c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/"
                + dbname, username, password);
        System.out.println("Opened database successfully");
    } catch (ClassNotFoundException | SQLException e) {
        System.err.println(e.getClass().getName() + ": " + e.getMessage() + "nnn");
    }
    return c;
}

void viewAll(String tableName, long startDate, long endDate, Connection c, String path) {
    String query = "SELECT * FROM " + tableName + " WHERE CAST(receivedtime AS integer) BETWEEN ? AND ? ORDER BY source, receivedtime;";

    try (PreparedStatement stmt = c.prepareStatement(query)) {              //try with resources
        stmt.setLong(1, startDate);                                         //prepare query
        stmt.setLong(2, endDate);
        ResultSet rs = stmt.executeQuery();

        try {
            while (rs.next()) { ... }