One might need to show graphs in their app for a lot of reasons. You may want to let the user enter some data and plot the data on a graph and analyse it, or you may want to show some other statistics based on the information from weather, stocks, etc.

In this post I am gonna show you how to achieve this using the library GraphView by Jonas.
The good news is that the library is open source and can be used commercially. The library is distributed under the Apache v2 License(More information here).

Using the library is really easy.

The first step is to add the following dependency to you GRADLE file.

dependencies{
compile 'com.jjoe64:graphview:4.2.1'
}

Then just add the GraphView object in your layout using the following code.

<com.jjoe64.graphview.GraphView
        android:layout_width="match_parent"
        android:layout_height="200dip"
        android:id="@+id/graph" />

You need to place the code inside the xml file of your layout. You can change various properties like @id, width, size, etc.

Once you have added to the layout, you can add the data points programmatically inside the activity.
The following code shows one example.

GraphView graph = (GraphView) findViewById(R.id.graph);
LineGraphSeries<DataPoint> series = new LineGraphSeries<>(new DataPoint[] {
          new DataPoint(0, 1),
          new DataPoint(1, 5),
          new DataPoint(2, 3)
});
graph.addSeries(series);

In the above code, we create an object of GraphView, then find it using the @id that you assigned to it earlier.
Then, we create an object ‘series‘ of DataPoint, LineGraphSeries means that the graph will be a line graph. You can use the following for different types of graphs:
BarGraphSeries, PointsGraphSeries

The fun doesn’t end here. You can even mix up different chart types.
The following example illustrates how:

GraphView graph = (GraphView) findViewById(R.id.graph);
BarGraphSeries<DataPoint> series = new BarGraphSeries<>(new DataPoint[] {
    new DataPoint(0, -2),
    new DataPoint(1, 5),
    new DataPoint(2, 3),
    new DataPoint(3, 2),
    new DataPoint(4, 6)
});
graph.addSeries(series);

LineGraphSeries<DataPoint> series2 = new LineGraphSeries<>(new DataPoint[] {
    new DataPoint(0, 3),
    new DataPoint(1, 3),
    new DataPoint(2, 6),
    new DataPoint(3, 2),
    new DataPoint(4, 5)
});
graph.addSeries(series2);

Reference

You can even enable scrolling and zooming:

// first series is a line
        DataPoint[] points = new DataPoint[100];
        for (int i = 0; i < points.length; i++) {
            points[i] = new DataPoint(i, Math.sin(i*0.5) * 20*(Math.random()*10+1));
        }
        LineGraphSeries<DataPoint> series = new LineGraphSeries<>(points);

        // set manual X bounds
        graph.getViewport().setYAxisBoundsManual(true);
        graph.getViewport().setMinY(-150);
        graph.getViewport().setMaxY(150);

        graph.getViewport().setXAxisBoundsManual(true);
        graph.getViewport().setMinX(4);
        graph.getViewport().setMaxX(80);

        // enable scaling and scrolling
        graph.getViewport().setScalable(true);
        graph.getViewport().setScalableY(true);

        graph.addSeries(series);

Reference

I have created a Curve Fitting App, which makes use of this library.
You can download it from Play Store, and check out the code at GitHub.

Hope you found it useful!
If you have any comments/doubts

Manas Sharma

Ph.D. researcher at Friedrich-Schiller University Jena, Germany. I’m a physicist specializing in computational material science. I write efficient codes for simulating light-matter interactions at atomic scales. I like to develop Physics, DFT, and Machine Learning related apps and software from time to time. Can code in most of the popular languages. I like to share my knowledge in Physics and applications using this Blog and a YouTube channel.

manas.bragitoff.com/