I am trying to write to an excel(.xlsx) file using Apache poi, I included the apache poi dependencies in my pom.xml file. But I am getting the following exception in execution. The code and pom.xml is specified as follows. I am getting the exception in the following line. Code: Pom: Answer I think You'r missing some classes "UnsupportedFileFormatException" try to

NoClassDefFoundError: UnsupportedFileFormatException while using apache poi to write to an excel file

I am trying to write to an excel(.xlsx) file using Apache poi, I included the apache poi dependencies in my pom.xml file. But I am getting the following exception in execution.

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/poi/UnsupportedFileFormatException
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at test.ExcelWriting.main(ExcelWriting.java:24)
    Caused by: java.lang.ClassNotFoundException: org.apache.poi.UnsupportedFileFormatException
        at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        ... 13 more

The code and pom.xml is specified as follows.

I am getting the exception in the following line.

XSSFWorkbook myWorkBook = new XSSFWorkbook (fis);

Code:

package test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelWriting {

    public static void main(String[] args) throws IOException{
        File myFile = new File("/home/sabra/workspace/test/src/main/resources/test.xlsx");
        FileInputStream fis = new FileInputStream(myFile);

        // Finds the workbook instance for XLSX file
        XSSFWorkbook myWorkBook = new XSSFWorkbook (fis);

        // Return first sheet from the XLSX workbook
        XSSFSheet mySheet = myWorkBook.getSheetAt(0);

        Map<String, Object[]> data = new HashMap<String, Object[]>();
        data.put("7", new Object[] {7d, "Sonya", "75K", "SALES", "Rupert"});
        data.put("8", new Object[] {8d, "Kris", "85K", "SALES", "Rupert"});
        data.put("9", new Object[] {9d, "Dave", "90K", "SALES", "Rupert"});

        // Set to Iterate and add rows into XLS file
        Set<String> newRows = data.keySet();

        // get the last row number to append new data          
        int rownum = mySheet.getLastRowNum();         

        for (String key : newRows) {

            // Creating a new Row in existing XLSX sheet
            Row row = mySheet.createRow(rownum++);
            Object [] objArr = data.get(key);
            int cellnum = 0;
            for (Object obj : objArr) {
                Cell cell = row.createCell(cellnum++);
                if (obj instanceof String) {
                    cell.setCellValue((String) obj);
                } else if (obj instanceof Boolean) {
                    cell.setCellValue((Boolean) obj);
                } else if (obj instanceof Date) {
                    cell.setCellValue((Date) obj);
                } else if (obj instanceof Double) {
                    cell.setCellValue((Double) obj);
                }
            }
        }

        // open an OutputStream to save written data into XLSX file
        FileOutputStream os = new FileOutputStream(myFile);
        myWorkBook.write(os);
        myWorkBook.close();
    }
}

Pom:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>test</groupId>
  <artifactId>test</artifactId>
  <version>0.0.1-SNAPSHOT</version>

  <dependencies>
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>3.8</version>
    </dependency>
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>3.11-beta2</version>
    </dependency>
  </dependencies>
</project>

Answer

I think You’r missing some classes “UnsupportedFileFormatException”

try to change the poi versions to the same and dont use the 3.11-beta2

You can use both in version 3.12 http://mvnrepository.com/artifact/org.apache.poi

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Answer