Visualize a multiple lines graph with JFreeChart in Java

For a Java user sometimes there is a data task to visualize how a certain variable changes in time. For that you can use JFreeChart. And if there are many variables, no problem there is JFreeChart. JFreeChart is an open source library and it is free to use. In this example we visualize a series of lines that represent how variables change on time.

A very self explanatory code for the above task is also the following one :

The code we will :

1 - generate an interval of values to use it for each line

2 - make the methods for representing the multiple lines graph itself

The Java code for the multiple lines graphic is ready to use and you can copy paste it in your Eclipse IDE after importing the jfreechart.jar file in your project

public class MultipleLinesChart extends JFrame { // the class extends the JFrame class

public MultipleLinesChart() {   // the constructor will contain the panel of a certain size and the close operations 
    super("XY Line Chart Example with JFreechart"); // calls the super class constructor
    
    JPanel chartPanel = createChartPanel();       
    add(chartPanel, BorderLayout.CENTER);
    
    setSize(640, 480);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
}

private JPanel createChartPanel() { // this method will create the chart panel containin the graph 
    String chartTitle = "Objects Movement Chart";
    String xAxisLabel = "X";
    String yAxisLabel = "Y";
    
    XYDataset dataset = createDataset();
    
    JFreeChart chart = ChartFactory.createXYLineChart(chartTitle, 
            xAxisLabel, yAxisLabel, dataset);

    customizeChart(chart);
    
    // saves the chart as an image files
    File imageFile = new File("XYLineChart.png");
    int width = 640;
    int height = 480;
    
    try {
        ChartUtilities.saveChartAsPNG(imageFile, chart, width, height);
    } catch (IOException ex) {
        System.err.println(ex);
    }
    
    return new ChartPanel(chart);
}

private XYDataset createDataset() {    // this method creates the data as time seris 
    XYSeriesCollection dataset = new XYSeriesCollection();
    XYSeries series1 = new XYSeries("Object 1");
    XYSeries series2 = new XYSeries("Object 2");
    XYSeries series3 = new XYSeries("Object 3");
    
    series1.add(1.0, 2.0);
    series1.add(2.0, 3.0);
    series1.add(3.0, 2.5);
    series1.add(3.5, 2.8);
    series1.add(4.2, 6.0);
    
    series2.add(2.0, 1.0);
    series2.add(2.5, 2.4);
    series2.add(3.2, 1.2);
    series2.add(3.9, 2.8);
    series2.add(4.6, 3.0);
    
    series3.add(1.2, 4.0);
    series3.add(2.5, 4.4);
    series3.add(3.8, 4.2);
    series3.add(4.3, 3.8);
    series3.add(4.5, 4.0);
    
    dataset.addSeries(series1);
    dataset.addSeries(series2);
    dataset.addSeries(series3);
    
    return dataset;
}

private void customizeChart(JFreeChart chart) {   // here we make some customization
    XYPlot plot = chart.getXYPlot();
    XYLineAndShapeRenderer renderer = new XYLineAndShapeRenderer();

    // sets paint color for each series
    renderer.setSeriesPaint(0, Color.RED);
    renderer.setSeriesPaint(1, Color.GREEN);
    renderer.setSeriesPaint(2, Color.YELLOW);

    // sets thickness for series (using strokes)
    renderer.setSeriesStroke(0, new BasicStroke(4.0f));
    renderer.setSeriesStroke(1, new BasicStroke(3.0f));
    renderer.setSeriesStroke(2, new BasicStroke(2.0f));
    
    // sets paint color for plot outlines
    plot.setOutlinePaint(Color.BLUE);
    plot.setOutlineStroke(new BasicStroke(2.0f));
    
    // sets renderer for lines
    plot.setRenderer(renderer);
    
    // sets plot background
    plot.setBackgroundPaint(Color.DARK_GRAY);
    
    // sets paint color for the grid lines
    plot.setRangeGridlinesVisible(true);
    plot.setRangeGridlinePaint(Color.BLACK);
    
    plot.setDomainGridlinesVisible(true);
    plot.setDomainGridlinePaint(Color.BLACK);
    
}

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            new MultipleLinesChart().setVisible(true);
        }
    });
}

}

And this is the result we have after running the code .

With JFreeChart it is pretty easy to make even more data visualizations.

There are many other guides in DataTreeMap and if you liked this guide please follow .
See you next time with more interesting guides on data visualization.