Read/write to same excel file using Apache POI

Question

i want to read an excel and write to the same excel based on some conditions. for example

     Empno  Name Salary
       1     jonh 2000
       2     Sam  3000
       3     Dean 7000

Now my requrient is

1) want to read the data based on column name say 'Name' and get all the data under that column

2) in the same way based on the column name say 'Name' i want to add one more row of data ie data should be in the following way after adding new row to same excel file

       Empno  Name Salary
       1     jonh  2000
       2     Sam   3000
       3     Dean  7000
       4     Smith  8000

how to do this using Apache POI.

can anybody provide me an example . i want to read/read to the same excel donot want to create a new excel.

thanks in advance.

Answer 1

You can refer below my sample program it may help you.

package com.sam.test.excel;
/**
 * @author Saminathan
 *
 */
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import org.apache.poi.POIXMLProperties;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFFont;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

/**
 * Sample Java program to read and write Excel file in Java using Apache POI
 * 
 */
public class FinalFormattingExcelWriting {
@SuppressWarnings("resource")
public static void main(String[] args) throws IOException,
        InvalidFormatException {
    FinalFormattingExcelWriting exl = new FinalFormattingExcelWriting();
    // adding student info into sheet
    exl.print("Student", "1", "Student1", "abc", 50, 78, 56, 55, 46);
    exl.print("Student", "2", "Student2", "def", 60, 54, 89, 66, 79);
    exl.print("Student", "3", "Student3", "ghi", 7, 96, 75, 88, 19);
    exl.print("Student", "4", "Student4", "jkl", 89, 15, 35, 44, 78);
    exl.print("Student", "5", "Student5", "mno", 40, 49, 46, 77, 46);
    exl.print("Student", "6", "Student6", "pqr", 56, 45, 57, 44, 44);
    exl.print("Student", "7", "Student7", "stu", 78, 61, 99, 66, 88);
    exl.print("Student", "8", "Student8", "vwx", 91, 39, 40, 22, 38);
    exl.print("Student", "9", "Student9", "yz", 45, 78, 49, 77, 59);
    exl.print("Student", "10", "Student10", "abc1", 77, 65, 77, 95, 46);
    System.out.println("Task Completed........................");
}

/*
 * Existing sheet and new sheet adding process
 */
@SuppressWarnings("resource")
public void print(String excelSheetName, String dataForRollNo,
        String dataForName, String dataForDept, int dataForSubj1,
        int dataForSubj2, int dataForSubj3, int dataForSubj4,
        int dataForSubj5) throws IOException {
    XSSFWorkbook workbook = null;
    File file = new File("D:/workspace/ex/examples/src/Student_Sheet.xlsx");
    FileOutputStream out = null;
    XSSFSheet excelSheet = null;
    CellStyle style = null;
    XSSFFont font = null;
    Map<String, Object[]> excelData = new TreeMap<String, Object[]>();
    // verifying file is present or not
    if (file.exists()) {
        FileInputStream inputStream = new FileInputStream(file);
        workbook = new XSSFWorkbook(inputStream);
        // verifying the sheet is available or not
        if (workbook.getSheet(excelSheetName) != null) {
            excelSheet = workbook.getSheet(excelSheetName);
        } else {
            excelSheet = workbook.createSheet(excelSheetName);
            // Style details for heading in new sheet
            style = workbook.createCellStyle();
            style.setFillForegroundColor(HSSFColor.GREEN.index);
            style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
            font = workbook.createFont();
            font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
            font.setColor(HSSFColor.WHITE.index);
            style.setFont(font);
            excelData.put("0", new Object[] { "RollNo", "Name", "Dept",
                    "Subj1", "Subj2", "Subj3", "Subj4", "Subj5", "Total",
                    "Avg", "Result" });
            addIntoCell(excelData, excelSheet, "0", style);
        }
    } else {
        workbook = new XSSFWorkbook();
        if (workbook.getSheet(excelSheetName) != null) {
            excelSheet = workbook.getSheet(excelSheetName);
        } else {
            excelSheet = workbook.createSheet(excelSheetName);
            // Style details for heading in new sheet
            style = workbook.createCellStyle();
            style.setFillForegroundColor(HSSFColor.GREEN.index);
            style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
            font = workbook.createFont();
            font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
            font.setColor(HSSFColor.WHITE.index);
            style.setFont(font);
            excelData.put("0", new Object[] { "RollNo", "Name", "Dept",
                    "Subj1", "Subj2", "Subj3", "Subj4", "Subj5", "Total",
                    "Avg", "Pass/Fail" });
            addIntoCell(excelData, excelSheet, "0", style);
        }
    }
    // adding author name in excel sheet
    POIXMLProperties xmlProps = workbook.getProperties();
    POIXMLProperties.CoreProperties coreProps = xmlProps
            .getCoreProperties();
    coreProps.setCreator("Saminathan");
    // This data needs to be written (Object[])
    // Data calculation
    int dataForTotal = dataForSubj1 + dataForSubj2 + dataForSubj3
            + dataForSubj4 + dataForSubj5;
    double dataForAvg = dataForTotal / 5;
    String dataForResult = "Fail";
    if (dataForAvg > 55) {
        dataForResult = "Pass";
    }
    excelData.put(dataForRollNo,
            new Object[] { dataForRollNo, dataForName, dataForDept,
                    dataForSubj1, dataForSubj2, dataForSubj3, dataForSubj4,
                    dataForSubj5, dataForTotal,
                    Double.toString(dataForAvg), dataForResult });
    addIntoCell(excelData, excelSheet, dataForRollNo, style);
    try {
        // Write the workbook in file system
        out = new FileOutputStream(file);
        workbook.write(out);
        workbook.close();
        out.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

// Inserting values into cell
public void addIntoCell(Map<String, Object[]> data, XSSFSheet sheet,
        String excelID, CellStyle style) {
    Set<String> keyset = data.keySet();
    Cell cell = null;
    Row row = null;
    Object[] objArr = null;
    int rownum = 0;
    if (Integer.parseInt(excelID) >= 1) {
        rownum = Integer.parseInt(excelID);
    }
    for (String key : keyset) {
        row = sheet.createRow(rownum);
        objArr = data.get(key);
        int cellnum = 0;
        for (Object obj : objArr) {
            cell = row.createCell(cellnum++);
            if (obj instanceof String) {
                cell.setCellValue((String) obj);
            } else if (obj instanceof Integer) {
                cell.setCellValue((Integer) obj);
            }
            // applying style only for heading
            if (Integer.parseInt(excelID) < 1) {
                cell.setCellStyle(style);
                }
            }
        }
    }
}

The output will be like Good Luck...!!! :)