Adding date/time to JFreeChart graph

Question

I currently have a method which queries a database for values, and plots them to a graph. The only problem is, the `time` variable is a long, and results in my graph looking like this: I want to convert it to a date format and then add it to the graph. How can I do this? Here is my graph code: ``` private Long time; private Long intensity; public XYSeries series = new XYSeries("Sensor"); private XYDataset xyDataset; public JFreeChart chart; xyDataset = new XYSeriesCollection(series); chart = ChartFactory.createXYLineChart("Sensor Data", "Time", "Intensity", xyDataset, PlotOrientation.VERTICAL, true, true, false); ``` Here is my method for adding to the graph: ``` public void GetDustLevels() { series.clear(); try { currentSensor = Application.getInstance().getMinesite().getSensors().get(sensorID); } catch (Exception e1) { e1.printStackTrace(); } if (currentSensor != null) { sensorKDTree = currentSensor.getSensorData(); Iterator, String>> allPoints = sensorK…

Accepted Answer

Without an sscce or the desired format, I'm just guessing at a suitable `DateFormat`.

```
XYPlot plot = (XYPlot) chart.getPlot();
DateAxis axis = (DateAxis) plot.getDomainAxis();
axis.setDateFormatOverride(DateFormat.getDateInstance());
```

Addendum: Looking closer at your update, you're using `ChartFactory.createXYLineChart()`, which creates a `NumberAxis` for the domain. Instead, use `ChartFactory.createTimeSeriesChart()`, which creates a `DateAxis` for the domain.

Addendum: If `time` represents milliseconds from the same epoch as a Java `Date`, you can use `new Date(time.longValue())` to construct your dataset's `RegularTimePeriod`. There's a related example here.

Adding date/time to JFreeChart graph

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