如何在动态jfreechart中显示点？

Question

我正在构建一个使用RFID标签跟踪物体位置的系统。我拥有一切，并认为该程序应该工作并编写这个动态Jfreechart，但没有显示点。

如何获得积分？

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.AbstractAction; 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.NumberTickUnit;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYItemRenderer;
import org.jfree.data.xy.XYDataItem;
import org.jfree.data.xy.XYDataset;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

public class TrackingChart extends JFrame
{   
   private static final String title = "RFID Tracking";
   private XYSeries moved = new XYSeries("Tags");
   private final Timer timer;
   private Table<String, Integer, Integer> tgs = HashBasedTable.create();

   public TrackingChart(String s)
   {
    super(s);
    update();
    final ChartPanel chartPanel = createDemoPanel();
    this.add(chartPanel, BorderLayout.CENTER);
    JPanel control = new JPanel();
    HashTableScatter app = new HashTableScatter();


    timer = new Timer(100, new ActionListener() {
        @Override 
        public void actionPerformed(ActionEvent e) {
            moved.clear();
            update();
        }
    });

    control.add(new JButton(new AbstractAction("Start") {
        @Override
        public void actionPerformed(ActionEvent e) {
            app.run("169.254.2.132");
            timer.start();
            tgs = app.gettgs();
        }
    }));

    control.add(new JButton(new AbstractAction("Stop") {
        @Override
        public void actionPerformed(ActionEvent e) {
            app.halt();
            timer.stop();
        }
    }));

    this.add(control, BorderLayout.SOUTH);
    }
    public double getx(int x, int y, int d)
    {
    /*
    * RSSI = TxPower - 10 * n * lg(d)
    * n = 2 (in free space)
    * 
    * d = 10 ^ ((TxPower - RSSI) / (10 * n))
    * max TxPower of Astra ex is -65 dbm will calibrate with more test  
    */
    double a = Math.pow(10, (-65 - x)/20);
    double b = Math.pow(10, (-65 - y)/20);
    double xpo = (b*b - a*a -d*d)/(-2d);
    return xpo;
    }

 public double gety(int x, int y, int d)
 {
   double a = Math.pow(10, (-65 - x)/20);
   double b = Math.pow(10, (-65 - y)/20);
   double xpo = (b*b - a*a -d*d)/(-2d);
   double ypo = Math.sqrt(a*a - xpo*xpo);
   return ypo;
 } 

    private void update() {
        String[] as = tgs.rowKeySet().toArray(new String [tgs.rowKeySet().size()]);
        for (int i = 0; i < tgs.rowKeySet().size(); i++) {
           int a;
           int b;
           Integer x = tgs.get(as[i], 1);
           if(x == null)
           {
               x = 0;
               a = x;
           }
           else
           {
               a = x;
           }
           Integer y = tgs.get(as[i], 2);
           if(y == null)
           {
               y = 0;
               b = y;
           }
           else
           {
               b = y;
           }
           double xs = getx(a,b,10);
           double ys = gety(a,b,10);
           moved.add(new XYDataItem(xs,ys));
        }
    }

private ChartPanel createDemoPanel() {
    JFreeChart jfreechart = ChartFactory.createScatterPlot(
        title, "X", "Y", createSampleData(),
        PlotOrientation.VERTICAL, true, true, false);
    XYPlot xyPlot = (XYPlot) jfreechart.getPlot();
    XYItemRenderer renderer = xyPlot.getRenderer();
    NumberAxis domain = (NumberAxis) xyPlot.getDomainAxis();
    domain.setRange(0, 10);
    domain.setTickUnit(new NumberTickUnit(1));
    NumberAxis range = (NumberAxis) xyPlot.getRangeAxis();
    range.setRange(0, 10);
    range.setTickUnit(new NumberTickUnit(1));
    return new ChartPanel(jfreechart){

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(640, 480);
        }
    };
}

private XYDataset createSampleData() {
    XYSeriesCollection xySeriesCollection = new XYSeriesCollection();
    xySeriesCollection.addSeries(moved);
    return xySeriesCollection;
}



      public static void main(String args[]) throws InterruptedException {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {

            TrackingChart demo = new TrackingChart(title);
            demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            demo.pack();
            demo.setLocationRelativeTo(null);
            demo.setVisible(true);
        }
    });
  }
}