How to use XYSeries in java without keeping track of the whole history, for displaying heartbeats?

Question

I followed a guide on youtube to make a java program that reads from serial port, which is connected to arduino uno, and display the readings on a jfreechart XYSeries graph. I am trying to display heartbeats using a heartbeat sensor connected to arduino, and the arduino is connected via serial port. I have managed to display the readings on a graph, but the graph keeps track of the readings from the beginning, however, I would like it to only display the last second or something so that the graph looks like real heartbeat readings. Here is the code where I plot the values

        series = new XYSeries("Heart Reading");
        XYSeriesCollection dataset = new XYSeriesCollection(series);
        JFreeChart chart = ChartFactory.createXYLineChart(
                "Your heartbeats", "Time (seconds)", "ADC Reading", dataset);
        window.add(new ChartPanel(chart), BorderLayout.CENTER);

        port = SerialPort.getCommPort("COM5");
        if(port.openPort()){
            System.out.println("Success");
            port.setComPortTimeouts(SerialPort.TIMEOUT_SCANNER, 0, 0);
            port.setBaudRate(9600);

            Thread thread = new Thread(){
                @Override public void run() {
                    Scanner scanner = new Scanner(port.getInputStream());
                    while(scanner.hasNextLine()) {
                        try {
                            String line = scanner.nextLine();
                            int number = Integer.parseInt(line);
                            series.add(x++, number);
                            window.repaint();
                        } catch(Exception e) {}
                    }
                    scanner.close();
                }
            };
            thread.start();

I know the problem is i'm only adding values without removing them, but how can I remove values if they are that many?

score 0 · Answer 1 · answered Feb 20 '16 at 05:38

Since you want to delete elements of your XYSeries, why not use the delete() method of the XYSeries class?

Once your series is a certain length, you can start delete an element at the beginning for each element you add at the end.

Unless I'm missing something obvious, this seems pretty darn easy.

How to use XYSeries in java without keeping track of the whole history, for displaying heartbeats?

1 Answers1