Apache POI Manage Scatter Chart

The default scatter chart in Excel always has lines between the data points.

If you are looking at the example code, there is a method private static void solidLineSeries which formats those lines to have colored fill.

What you need is a private static void setLineNoFill which sets a not filled line between the data points.

Additional you need set XDDFScatterChartData.Series marker style and marker size using XDDFScatterChartData.Series.setMarkerStyle and XDDFScatterChartData.Series.setMarkerSize.

Complete Example:

import java.io.FileOutputStream;
import java.io.IOException;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xddf.usermodel.*;
import org.apache.poi.xddf.usermodel.chart.*;
import org.apache.poi.xssf.usermodel.*;

/**
 * Illustrates how to create a simple scatter chart.
 */
public class ScatterChart {

    public static void main(String[] args) throws IOException {
        try (XSSFWorkbook wb = new XSSFWorkbook()) {
            XSSFSheet sheet = wb.createSheet("Sheet 1");
            final int NUM_OF_ROWS = 3;
            final int NUM_OF_COLUMNS = 10;

            // Create a row and put some cells in it. Rows are 0 based.
            Row row;
            Cell cell;
            for (int rowIndex = 0; rowIndex < NUM_OF_ROWS; rowIndex++) {
                row = sheet.createRow((short) rowIndex);
                for (int colIndex = 0; colIndex < NUM_OF_COLUMNS; colIndex++) {
                    cell = row.createCell((short) colIndex);
                    cell.setCellValue(colIndex * (rowIndex + 1.0));
                }
            }

            XSSFDrawing drawing = sheet.createDrawingPatriarch();
            XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 5, 10, 15);

            XSSFChart chart = drawing.createChart(anchor);
            XDDFChartLegend legend = chart.getOrAddLegend();
            legend.setPosition(LegendPosition.TOP_RIGHT);

            XDDFValueAxis bottomAxis = chart.createValueAxis(AxisPosition.BOTTOM);
            bottomAxis.setTitle("x"); // https://stackoverflow.com/questions/32010765
            XDDFValueAxis leftAxis = chart.createValueAxis(AxisPosition.LEFT);
            leftAxis.setTitle("f(x)");
            leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

            XDDFDataSource<Double> xs = XDDFDataSourcesFactory.fromNumericCellRange(sheet, new CellRangeAddress(0, 0, 0, NUM_OF_COLUMNS - 1));
            XDDFNumericalDataSource<Double> ys1 = XDDFDataSourcesFactory.fromNumericCellRange(sheet, new CellRangeAddress(1, 1, 0, NUM_OF_COLUMNS - 1));
            XDDFNumericalDataSource<Double> ys2 = XDDFDataSourcesFactory.fromNumericCellRange(sheet, new CellRangeAddress(2, 2, 0, NUM_OF_COLUMNS - 1));


            XDDFScatterChartData data = (XDDFScatterChartData) chart.createData(ChartTypes.SCATTER, bottomAxis, leftAxis);
            XDDFScatterChartData.Series series1 = (XDDFScatterChartData.Series) data.addSeries(xs, ys1);
            series1.setTitle("2x", null); // https://stackoverflow.com/questions/21855842
            series1.setSmooth(false); // https://stackoverflow.com/questions/39636138

            series1.setMarkerStyle(MarkerStyle.CIRCLE);
            series1.setMarkerSize((short)5);
            setLineNoFill(series1);

            XDDFScatterChartData.Series series2 = (XDDFScatterChartData.Series) data.addSeries(xs, ys2);
            series2.setTitle("3x", null);

            series2.setMarkerStyle(MarkerStyle.CIRCLE);
            series2.setMarkerSize((short)5);
            setLineNoFill(series2);

            chart.plot(data);

            // Write the output to a file
            try (FileOutputStream fileOut = new FileOutputStream("ooxml-scatter-chart.xlsx")) {
                wb.write(fileOut);
            }
        }
    }

    private static void setLineNoFill(XDDFScatterChartData.Series series) {
        XDDFNoFillProperties noFillProperties = new XDDFNoFillProperties();
        XDDFLineProperties lineProperties = new XDDFLineProperties();
        lineProperties.setFillProperties(noFillProperties);
        XDDFShapeProperties shapeProperties = series.getShapeProperties();
        if (shapeProperties == null) shapeProperties = new XDDFShapeProperties();
        shapeProperties.setLineProperties(lineProperties);
        series.setShapeProperties(shapeProperties);
    }
}