Read data from CSV file into ArrayList and display in XY Chart

Question

I would like to display a temperature curve over time. I have now read a file, which is CSV-similar, that let me know the time and the temperature indicated. Now I want to use JFreeChart to display an XY graph from the values. The original data of the file looks as follows:

utc,local,celsius
2017-07-12T07:02:53+00:00,2017-07-12T09:02:53+02:00,26.25
2017-07-12T08:02:54+00:00,2017-07-12T10:02:54+02:00,26.08
2017-07-12T09:02:55+00:00,2017-07-12T11:02:55+02:00,25.78
2017-07-12T10:02:56+00:00,2017-07-12T12:02:56+02:00,25.96
2017-07-12T10:51:02+00:00,2017-07-12T12:51:02+02:00,26.14
2017-07-12T10:51:02+00:00,2017-07-12T12:51:02+02:00,26.14

The output of time & temperature values (I have separated from the original file) looks like:

09:02:53,26.25
10:02:54,26.08
11:02:55,25.78
12:02:56,25.96
12:51:02,26.14
12:51:02,26.14

EDIT: Now I have inserted a DateTimeFormatter in the example from Trashgod: It looks like:

public class Test {
public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
        ApplicationFrame frame = new ApplicationFrame("CSVTest");
        Test test = new Test();
        frame.add(test.createChart("Temperature profile"));
        frame.pack();
        frame.setLocationRelativeTo(null);;
        frame.setVisible(true);
    });
}

private ChartPanel createChart(String chartTitle) {
    JFreeChart chart = ChartFactory.createTimeSeriesChart(chartTitle,
        "Time", "Temperature", createDataset(), true, true, false);
    ChartPanel chartPanel = new ChartPanel(chart);
    XYPlot plot = chart.getXYPlot();
    DateAxis domain = (DateAxis) plot.getDomainAxis();
    domain.setDateFormatOverride(DateFormat.getDateInstance());
    plot.setBackgroundPaint(Color.WHITE);
    return chartPanel;
}


    private XYDataset createDataset() {
    TimeSeries series = new TimeSeries("Temperature");
    TimeSeriesCollection dataset = new TimeSeriesCollection(series);
    try (FileReader fr = new FileReader("TestCSV.csv");
        BufferedReader br = new BufferedReader(fr)) {
        String line;
        br.readLine();
        while ((line = br.readLine()) != null) {
            String[] split = line.split(",");

           System.out.println(ZonedDateTime.parse(split[1]).format(DateTimeFormatter.ISO_LOCAL_TIME)  + "," +split[2]);
           ZonedDateTime zdt = ZonedDateTime.of(LocalDate.now(),LocalTime.parse(split[0]), ZoneId.systemDefault());
           String s = ZonedDateTime.parse(split[0]).format(DateTimeFormatter.ISO_LOCAL_TIME);

           Second second =  new Second(Date.from(zdt.toInstant()));
           series.add(second, Double.valueOf(split[1]));
        }
    } catch (IOException | SeriesException e) {
        System.err.println("Error: " + e);
    }
    return dataset;
}

The first line of the "CSV" -like file is still displayed 09:02:53,26.25 Then I get a DateTimeParseException: Text '2017-07-12T09:02:53+02:00' could not be parsed at index 2

Exception in thread "AWT-EventQueue-0" java.time.format.DateTimeParseException: Text '2017-07-12T07:02:53+00:00' could not be parsed at index 2
at java.time.format.DateTimeFormatter.parseResolved0(Unknown Source)
at java.time.format.DateTimeFormatter.parse(Unknown Source)
at java.time.LocalTime.parse(Unknown Source)
at java.time.LocalTime.parse(Unknown Source)
at org.jfree.chart.demo.Test.createDataset(Test.java:63)
at org.jfree.chart.demo.Test.createChart(Test.java:43)
at org.jfree.chart.demo.Test.lambda$0(Test.java:34)

Why can not the rest of the file be read nor displayed? ("System.out.println()" should only serve as a control at the end). The DateTimeFomatter is correct, isn´t it?

With your approach, the time to make locally I come no further & the program can not translate. What did I do wrong? How could it work if the direct output

09:02:53,26.25
10:02:54,26.08
11:02:55,25.78
12:02:56,25.96
12:51:02,26.14
12:51:02,26.14

is displayed in a chart? I think to split and to transform like I did is okay, isn´t it? Now I have setDateFormatOverride () in the code, but the error message, as well as the output remain the same.

Answer 1

Several problems are evident:

• You never add anything to lines; at a minimum, you'll need something like this:

  lines.add(line);
  

• Instead of ChartFactory.createXYLineChart(), consider creating a time series:

  ChartFactory.createTimeSeriesChart(…)
  

• The XYDataset returned by createDataset() should be a TimeSeriesCollection to which you add a TimeSeries.

• In createDataset(), iterate though lines, parse the data fields, and add the values to the TimeSeries.

• The time values given are most closely modeled by LocalTime, but TimeSeries expects to add() coordinates defined by a RegularTimePeriod and a double; see Legacy Date-Time Code concerning the conversion shown below.

• Note that TimeSeries throws SeriesException for duplicate domain values; as a result, only three of the four lines int eh sample input air charted.

• Instead of replacing the factory supplied XYLineAndShapeRenderer, get a reference to it for later modification.

• Alter the chart's size using one of the approaches shown here.

• Avoid extending top-level containers line ApplicationFrame.

• Construct and manipulate Swing GUI objects only on the event dispatch thread.

• Use a try-with-resources statement to ensure that each resource is closed at the end of the statement.

• As your actual data contains ISO 8601 dates, ZonedDateTime.parse() can be used directly; use setDateFormatOverride() to format the date axis labels; the example below specifies a UTC time zone in ISO 8601 format for easy comparison; comment out the call to setDateFormatOverride() to see the times in your local time zone.

import java.awt.Color;
import java.awt.EventQueue;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.time.ZonedDateTime;
import java.util.Date;
import java.util.TimeZone;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.general.SeriesException;
import org.jfree.data.time.Second;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;

/** @see https://stackoverflow.com/a/45173688/230513 */
public class CSVTest {

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            ApplicationFrame frame = new ApplicationFrame("CSVTest");
            CSVTest test = new CSVTest();
            frame.add(test.createChart("Temperature profile"));
            frame.pack();
            frame.setLocationRelativeTo(null);;
            frame.setVisible(true);
        });
    }

    private ChartPanel createChart(String chartTitle) {
        JFreeChart chart = ChartFactory.createTimeSeriesChart(chartTitle,
            "Time", "Temperature", createDataset(), true, true, false);
        ChartPanel chartPanel = new ChartPanel(chart);
        XYPlot plot = chart.getXYPlot();
        plot.setBackgroundPaint(Color.WHITE);
        XYLineAndShapeRenderer r = (XYLineAndShapeRenderer) plot.getRenderer();
        r.setBaseShapesVisible(true);
        DateAxis axis = (DateAxis) plot.getDomainAxis();
        SimpleDateFormat df = new SimpleDateFormat("HH:mm:ssX");
        df.setTimeZone(TimeZone.getTimeZone("UTC"));
        axis.setDateFormatOverride(df);
        return chartPanel;
    }

    private XYDataset createDataset() {
        TimeSeries series = new TimeSeries("Temperature");
        TimeSeriesCollection dataset = new TimeSeriesCollection(series);
        try (FileReader fr = new FileReader("temp.csv");
            BufferedReader br = new BufferedReader(fr)) {
            String line;
            while ((line = br.readLine()) != null) {
                String[] s = line.split(",");
                ZonedDateTime zdt = ZonedDateTime.parse(s[0]);
                Second second = new Second(Date.from(zdt.toInstant()));
                series.add(second, Double.valueOf(s[2]));
            }
        } catch (IOException | SeriesException e) {
            System.err.println("Error: " + e);
        }
        return dataset;
    }
}