Strip Chart

Summary

This demo illustrates how the JMSL Library can easily be used to build a Java™ application that incorporates live data. In this case, the application is of a strip chart display..

Usage

The Lines menu bar lets you select which lines are plotted on the chart.

JMSL Library Charting Classes

The chart is a traditional set of line graphs of random data. When the menu item is selected or deselected, an internal class is used to set the paint attribute for that Data object:

jMenuItem.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent evt) {
        data[index].setPaint(jMenuItem.getState());
    }
});

Java Code

The animation is accomplished by using a separate thread. The thread is started in the main() method:

Thread thread = new Thread(strip);
thread.setDaemon(true);
thread.start();

This code then calls the run() method of Strip because it implements Runnable, which updates the chart. Note the try/catch block and the Thread.sleep() call. Also note that the paint() method of Strip must be synchronized.

public void run() {
    int n = y[0].length;
    float t = 0;
    while (true) {
        synchronized (this) {
            t += 1.0f;
            label.setTitle("Current Time "+t);
            for (int i = 0; i < y.length; i++) {
                for (int k = n-1; k > 0; k--) {
                    y[i][k] = y[i][k-1];
                }
                y[i][0] += 0.10*Math.random() - 0.05;
                if (Math.abs(y[i][0]) > 1) y[i][0] = 0.0;
            }
        }
        repaint();
        try {
            Thread.sleep(50);
        } catch (Exception e) {
        }
    }
}

Link to Source Code

Running This Demo

Two alternatives are available to run this demo:

1) Use the source code in your development environment as any other Java code. More information is available in the How To.

2) An executable jar file containing all of the demos referenced in this guide is included in the jmsl/lib directory. On Windows, you may double-click the file to run it if files with a ".jar" extension are properly registered with javaw.exe. Alternatively, for both Windows and UNIX environments, the jar file may be executed from the command line using java -jar gallery.jar.

As list of buttons, one for each demo, is created. Demos can be subsetted as they relate to specific areas (Math, Stat, Finance, Charting) by choosing the appropriate selection on the JComboBox. To run the Additional Demos, select Quick Start in the JComboBox.