XYItemLabelGenerator

public class LineChartDemo6{
public static void main(String arg[]){
  XYSeries series = new XYSeries("Average Weight");
  series.add(20.0, 20.0);
  series.add(40.0, 20.0);
  series.add(55.0, 20.0);
  series.add(70.0, 20.0);
  XYDataset xyDataset = new XYSeriesCollection(series);
    JFreeChart chart = ChartFactory.createXYLineChart
  ("XYLine Chart using JFreeChart", "Age", "Weight",
 xyDataset, PlotOrientation.VERTICAL, true, true, false);
    XYPlot plot = chart.getXYPlot();
    XYLineAndShapeRenderer renderer = (XYLineAndShapeRenderer) plot.getRenderer();
    NumberFormat format = NumberFormat.getNumberInstance();
    format.setMaximumFractionDigits(2); // etc.
    XYItemLabelGenerator generator = new StandardXYItemLabelGenerator("{0} {1} {2} {3}", format, format);
    renderer.setBaseItemLabelGenerator(generator);
    renderer.setBaseItemLabelsVisible(true);
  ChartFrame frame1=new ChartFrame("XYLine Chart",chart);
  frame1.setVisible(true);
  frame1.setSize(300,300);
  }
}