Question

I am facing some problems with JFreeChart with Java.
I am retriving data from remote database to make them display in a Panel from my application.

1. The problem: when I get the data, it does not display directly on the panel. I have to minimize and maximize the form to make the data being loaded.

2. I need this data to be refreshing every minute. I was thinking about a Timer but I don’t really know how to integrate it.

Here is part of the code:

import java.io.BufferedReader;
import java.net.Socket;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.List;
import java.util.ArrayList;
import javax.swing.JPanel;

public class GetRequest implements Runnable{

    public BufferedReader _input = null;
    public Socket clientSocket = null;
    public DrawChart draw;
    public List<Double> values_1, values_2, values_3, values_4;
    public JPanel _panel;

    public GetRequest(Socket socket, JPanel panel){
        clientSocket = socket;
        draw = new DrawChart();
        _panel = panel;
        values_1 = new ArrayList<Double>();
        values_2 = new ArrayList<Double>();
        values_3 = new ArrayList<Double>();
    }

    @Override
    public void run(){
        while(true){

            try{
                _input = new BufferedReader(
                    new InputStreamReader(clientSocket.getInputStream ()));
                String line = _input.readLine ();

                String[] clineComat = line.split (",");
                for(int i = 0 ;i<clineComat.length;i++){

                    String[] clineSemiComa_ = clineComat[i].split (";");
                    System.out.println(">"+clineComat[i]);
                    values_1.add (Double.parseDouble (clineSemiComa_[0])+1);
                    values_2.add (Double.parseDouble (clineSemiComa_[1])+1);
                    values_3.add (Double.parseDouble (clineSemiComa_[2]));
                }

                EventQueue.invokeLater (new Runnable(){
                public void run(){
                    draw.displayPie (_panel, values_1, values_2, values_3);
                }
            });
            }
            catch(IOException e){e.printStackTrace ();}
        }
    }}

and this is the code of the DrawChart.java

import  org.jfree.chart.ChartFactory;
import  org.jfree.chart.ChartPanel;
import  org.jfree.chart.JFreeChart;
import  org.jfree.data.general.DefaultPieDataset;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import org.jfree.chart.plot.PlotOrientation;
import java.awt.Dimension;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.data.category.CategoryDataset;
import java.util.List;
import java.lang.Float;
import java.util.Timer;
import java.util.TimerTask;

public class DrawChart {

    public void displayPie(JPanel jpanel, List<Double> values_1, List<Double> values_2, List<Double> values_3) {

        CategoryDataset data = createDataset(values_1, values_2, values_3);
        //create a chart...
        JFreeChart chart=ChartFactory.createBarChart ("", null, null, data, PlotOrientation.VERTICAL, true, true, false);
        chart = ChartFactory.createLineChart ("", null, null, data, PlotOrientation.VERTICAL, true, true, false);

        //create and display a frame...
        ChartPanel panel=new ChartPanel(chart);
        panel.setPreferredSize (new Dimension(700,300));
        jpanel.setLayout(new java.awt.BorderLayout());
        jpanel.add (panel, BorderLayout.CENTER);
        jpanel.setVisible(true);
        }

    public static CategoryDataset createDataset(List<Double> a, List<Double> b, List<Double> c) {

        String series1 = "Series1";
        String series2 = "Series2";
        String series3 = "Series3";

        final DefaultCategoryDataset dataset = new DefaultCategoryDataset();

        if(a.size () != 0 && b.size () != 0 && c.size () != 0 ) {

            for(int i=0;i<a.size ();i++) {
                dataset.addValue(a.get (i), series1, i+1+"");
            }

            for(int i=0;i<b.size ();i++) {
                dataset.addValue(b.get (i), series2, i+1+"");
            }

            for(int i=0;i<c.size ();i++) {
                dataset.addValue(c.get (i), series3, i+1+"");
            }

        }

        return dataset;
    }
}

How can I solve this ? Does anyone has done a similar ?
Thanks

Answer 1

I may be overlooking a JFreeChart problem, but drawing in Swing must occur on the event dispatch thread. In contrast, your call to displayPie() occurs from an anonymous Runnable in GetRequest. Common remedies include these:

• EventQueue.invokeLater, illustrated here.

• SwingWorker, illustrated here.

• javax.swing.Timer for periodic updates, illustrated here and here.