In this blog post, we will explore how to use Nashorn, which is a JavaScript engine in Java, for data visualization and charting. Nashorn provides a seamless integration between JavaScript and Java, allowing us to leverage popular JavaScript libraries for charting and creating interactive visualizations.

Table of Contents

• Introduction to Nashorn
• Installing Nashorn
• Using JavaScript Charting Libraries
• Creating Interactive Charts
• Conclusion

Introduction to Nashorn

Nashorn is a JavaScript engine that comes bundled with Java since Java 8. It allows executing JavaScript code within a Java application. With Nashorn, we can leverage existing JavaScript charting libraries to create stunning visualizations.

Installing Nashorn

To use Nashorn, make sure you have Java 8 or later installed on your machine. Java 8 comes with Nashorn built-in, so there is no additional installation required.

Using JavaScript Charting Libraries

Nashorn allows us to use popular JavaScript charting libraries such as D3.js, Chart.js, or Highcharts. These libraries provide a wide range of charts and options for data visualization.

To use a JavaScript library with Nashorn, we first need to load the library into the Nashorn context. Here’s an example of loading Chart.js:

load("https://cdn.jsdelivr.net/npm/chart.js");

var ctx = new JavaAdapter(javax.swing.JPanel, {
    paintComponent: function (g) {
        // Create chart using Chart.js
        var chart = new Chart(g, {
            type: 'bar',
            data: {
                labels: ['Red', 'Blue', 'Yellow', 'Green', 'Purple', 'Orange'],
                datasets: [{
                    label: '# of Votes',
                    data: [12, 19, 3, 5, 2, 3],
                    backgroundColor: 'rgba(75, 192, 192, 0.2)',
                    borderColor: 'rgba(75, 192, 192, 1)',
                    borderWidth: 1
                }]
            },
            options: {
                scales: {
                    y: {
                        beginAtZero: true
                    }
                }
            }
        });
    }
});

// Display the chart in a Java Swing application
var frame = new javax.swing.JFrame("Chart Example");
frame.setSize(400, 400);
frame.getContentPane().add(ctx);
frame.setVisible(true);

In this example, we load the Chart.js library using the load function, create a new Java Swing JPanel, and override the paintComponent function to create the chart using Chart.js.

Creating Interactive Charts

Nashorn also enables interactivity in the charts by binding Java objects to JavaScript. We can interactively update the chart data or options from Java. Here’s an example:

var chart = new Chart(g, {
    type: 'line',
    data: {
        labels: ['January', 'February', 'March', 'April', 'May', 'June', 'July'],
        datasets: [{
            label: 'Sales',
            data: [],
            backgroundColor: 'rgba(75, 192, 192, 0.2)',
            borderColor: 'rgba(75, 192, 192, 1)',
            borderWidth: 1
        }]
    },
    options: {
        scales: {
            y: {
                beginAtZero: true
            }
        }
    }
});

// Update chart data from Java
chart.data.datasets[0].data = [30, 10, 50, 20, 40, 30, 50];
chart.update();

In this example, we create a line chart and initially provide empty data. Later, we update the chart data from Java and call the update function to refresh the chart.

Conclusion

In this blog post, we explored how to use Nashorn for data visualization and charting. Nashorn allows us to seamlessly integrate JavaScript charting libraries with Java, opening up a wide range of possibilities for creating interactive charts and visualizations.

By using Nashorn, we can leverage the power of popular JavaScript charting libraries while staying within the Java ecosystem.

Stay tuned for more articles on using Nashorn and other Java technologies for innovative solutions!

#hashtags: #Nashorn #DataVisualization