How to update the contents displayed on a jFrame periodically

[Jay Crawf]

Hi everyone, I've been lurking around for awhile, I've created an account in frustration with trying to solve this problem.

I want to refresh the contents of a jFrame periodically after it is initially displayed by the user with a button click. The frame has a jFreeChart on it based on data read in from a file, and I want it to redraw the chart regularly showing any new data written to this input file.

I tried putting in a loop with a delay around the whole draw function and having the chart re-display that way, but the frame just turns black while the loop is running and never really updates...

I also tried branching out the re display to another thread, but this has likewise failed to do what I thought it would.

How might I be able to get the frame to update its display at some interval, while using any new data that may have been added to the input file?

code to display chart:

    private void ChartBtnActionPerformed(java.awt.event.ActionEvent evt) {                                         
     
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        
        jPanel1.setLayout(new java.awt.BorderLayout());

//        while(true){              <---- This doesn't work
//          frame.setVisible(true);
        
        try {
            dataset =getData(); //Obtain data set to chart
        } catch (FileNotFoundException ex) {
            Logger.getLogger(MainForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(MainForm.class.getName()).log(Level.SEVERE, null, ex);
        }

        final JFreeChart chart = ChartFactory.createLineChart(
            "Chart Title",       // chart title
            "Week",                    // domain axis label
            "Label1",                   // range axis label
            dataset,                   // data
            PlotOrientation.VERTICAL,  // orientation
            true,                      // include legend
            true,                      // tooltips
            false                      // urls
        );

        ChartPanel CP = new ChartPanel(chart);
        jPanel1.add(CP);
        jPanel1.validate();
        jPanel1.setVisible(true);
        CharmGraphFrame.setVisible(true);
        CharmGraphFrame.setSize(900,520);
//            try {
//                Thread.currentThread().sleep(8000);
//            } catch (InterruptedException ex) {
//                Logger.getLogger(MainForm.class.getName()).log(Level.SEVERE, null, ex);
//            }
//            frame.setVisible(false);
//        }

   
    }         

Code to read in from file:

    public DefaultCategoryDataset getData() throws FileNotFoundException, IOException{

        DefaultCategoryDataset datum = new DefaultCategoryDataset();

        String file = "state.txt";  //data to chart is on this file
        int x =0;
        BufferedReader br = new BufferedReader(new FileReader(file));
        String line;
        int c =count(file);
        if (c < 20){
          while ((line = br.readLine()) != null) {
                String hold = new String();
                hold = Integer.toString(x +1);

                datum.addValue(Double.parseDouble(line), "label", hold );
                x ++;
            }

        }
.
.
.
br.close();
return datum;

[Paul Clapham]

You use a Swing timer to do that. Here's a link to the tutorial: How to Use Swing Timers.

[Ranganathan Kaliyur Mannar]

and, Welcome to the Ranch!

[Randall Twede]

Paul beat me to the answer by approximately 24 hours

on the other hand, it is a kind of unusual thing to do. usually we rely on Action Events(or some kind of event anyway).

[Campbell Ritchie]

Doesn't a Swing Timer fire action events? Look in the Java Tutorials.