Code

@Override

public HashMap<String, ArrayList> getMeasurementsByDateRange(Date startDate, Date endDate, Classroom classroom) {

HashMap<String, ArrayList> MeasurementsByDateRange = new HashMap();

ArrayList<Double> co2 = new ArrayList<>();

ArrayList<Double> humidity = new ArrayList<>();

ArrayList<Double> temperature = new ArrayList<>();

PreparedStatement statement;

ResultSet resultSet;

try {

statement = connection.prepareStatement("SELECT co2.co2Value,humidity.humidityValue, temperature.temperatureValue, classroom.name, measurement.timestamp FROM kelvin.measurement\n"

+ "inner JOIN classroom on classroomId = measurement.classroomId\n"

+ " INNER JOIN co2 ON measurement.id = co2.measurementId\n"

+ " INNER JOIN humidity ON measurement.id = humidity.measurementId\n"

+ " INNER JOIN temperature ON temperature.id = temperature.measurementId\n"

+ " \n"

+ " WHERE (timestamp BETWEEN ? AND ?)");

statement.setDate(1, new java.sql.Date(startDate.getTime()));

statement.setDate(2, new java.sql.Date(endDate.getTime()));

resultSet = statement.executeQuery();

while (resultSet.next()) {

Double co2Value = resultSet.getDouble("co2Value");

Double humidityValue = resultSet.getDouble("humidityValue");

Double temperatureValue = resultSet.getDouble("temperatureValue");

co2.add(co2Value);

humidity.add(humidityValue);

temperature.add(temperatureValue);

}

MeasurementsByDateRange.put("co2Value", co2);

MeasurementsByDateRange.put("humidityValue", humidity);

MeasurementsByDateRange.put("temperatureValue", temperature);

} catch (SQLException ex) {

Logger.getLogger(MySqlMeasurementDAO.class.getName()).log(Level.SEVERE, null, ex);

}

return MeasurementsByDateRange;

}