Create Bar Chart in XLSX File - POI JFreeChart - Java Example Program

Bar Chart in Excel Using Java - XLSX Introduction

In this example, we will discuss how to create a bar chart in a XLSX format file, using Java, and Apache POI / JFreeChart libraries. We provided a XLS version of this tutorial earlier, where we generated a PNG chart in JFreeChart and added the chart to Excel using POI. We will aim to do the same in XLSX version also. You will have to refer to the XLS version to understand the input / output. We will provide only the Java program in this post.

XLSX - Bar Chart - Java Example Program

The Java program that generates a bar chart in a XLSX file, using POI / JFreeChart is provided below:

import java.io.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.util.IOUtils;
import org.apache.poi.hssf.usermodel.HSSFClientAnchor;
import org.jfree.data.category.DefaultCategoryDataset; 
import org.jfree.chart.ChartFactory;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.plot.PlotOrientation;
import java.util.Iterator;
public class CreateBarChartExampleXLSX {  
        public static void main(String[] args) throws Exception{                
                /* Read the bar chart data from the excel file */
                FileInputStream chart_file_input = new FileInputStream(new File("POIbarChart.xlsx"));
                /* XSSFWorkbook object reads the full Excel document. We will manipulate this object and
                write it back to the disk with the chart */
                XSSFWorkbook my_workbook = new XSSFWorkbook(chart_file_input);
                /* Read chart data worksheet */
                XSSFSheet my_sheet = my_workbook.getSheetAt(0);
                /* Create Dataset that will take the chart data */
                DefaultCategoryDataset my_bar_chart_dataset = new DefaultCategoryDataset();
                /* We have to load bar chart data now */
                /* Begin by iterating over the worksheet*/
                /* Create an Iterator object */
                Iterator<Row> rowIterator = my_sheet.iterator(); 
                /* Loop through worksheet data and populate bar chart dataset */
                String chart_label="a";
                Number chart_data=0;            
                while(rowIterator.hasNext()) {
                        //Read Rows from Excel document
                        Row row = rowIterator.next();  
                        //Read cells in Rows and get chart data
                        Iterator<Cell> cellIterator = row.cellIterator();
                                while(cellIterator.hasNext()) {
                                        Cell cell = cellIterator.next(); 
                                        switch(cell.getCellType()) { 
                                        case Cell.CELL_TYPE_NUMERIC:
                                                chart_data=cell.getNumericCellValue();
                                                break;
                                        case Cell.CELL_TYPE_STRING:
                                                chart_label=cell.getStringCellValue();
                                                break;
                                        }
                                }
                /* Add data to the data set */          
                /* We don't have grouping in the bar chart, so we put them in fixed group */            
                my_bar_chart_dataset.addValue(chart_data.doubleValue(),"Marks",chart_label);
                }               
                /* Create a logical chart object with the chart data collected */
                JFreeChart BarChartObject=ChartFactory.createBarChart("Subject Vs Marks","Subject","Marks",my_bar_chart_dataset,PlotOrientation.VERTICAL,true,true,false);  
                /* Dimensions of the bar chart */               
                int width=640; /* Width of the chart */
                int height=480; /* Height of the chart */               
                /* We don't want to create an intermediate file. So, we create a byte array output stream 
                and byte array input stream
                And we pass the chart data directly to input stream through this */             
                /* Write chart as PNG to Output Stream */
                ByteArrayOutputStream chart_out = new ByteArrayOutputStream();          
                ChartUtilities.writeChartAsPNG(chart_out,BarChartObject,width,height);
                /* We can now read the byte data from output stream and stamp the chart to Excel worksheet */
                int my_picture_id = my_workbook.addPicture(chart_out.toByteArray(), Workbook.PICTURE_TYPE_PNG);
                /* we close the output stream as we don't need this anymore */
                chart_out.close();
                /* Create the drawing container */
                XSSFDrawing drawing = my_sheet.createDrawingPatriarch();
                /* Create an anchor point */
                ClientAnchor my_anchor = new XSSFClientAnchor();
                /* Define top left corner, and we can resize picture suitable from there */
                my_anchor.setCol1(4);
                my_anchor.setRow1(5);
                /* Invoke createPicture and pass the anchor point and ID */
                XSSFPicture  my_picture = drawing.createPicture(my_anchor, my_picture_id);
                /* Call resize method, which resizes the image */
                my_picture.resize();
                /* Close the FileInputStream */
                chart_file_input.close();               
                /* Write changes to the workbook */
                FileOutputStream out = new FileOutputStream(new File("POIbarChart.xlsx"));
                my_workbook.write(out);
                out.close();            
        }
}

This program uses XSSF classes to write the chart back to the XLSX file, otherwise it is no different to the XLS example. It produces the same output as the XLS one. You can try this example on your chart data, and post a comment if your are stuck.