line chart using jfreechart

I have created line chart using jfreeChart API inside jsp and servlet.

Following is the code in servlet

// Get the output stream from the response object:
 OutputStream out = response.getOutputStream();
 
 // Set the HTTP Response Type:
 response.setContentType("image/png");
 
 XYSeries series = new XYSeries("Average Weight1233");
 series.add(1.48, 20.0);
 series.add(1.52, 25.0);
 series.add(2.02, 50.0);
 series.add(2.05, 65.0);
 series.add(3.30, 2);
 series.add(3.52, 50);
 XYDataset xyDataset = new XYSeriesCollection(series);
 
 // Create chart:
 JFreeChart chart
 = ChartFactory.createXYLineChart("XYLine Chart using JFreeChart",
                                  "Age", "Weight",xyDataset,
                                  PlotOrientation.VERTICAL,
                                  true, true, false);
 
 // Write the data to the output stream:
 ChartUtilities.writeChartAsPNG(out, chart, 400, 300);
 

It creates horizontal number automatically from values that I have added on XYSeries But I want to set that value manually.

Is it possible? How?

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