Can't Create an excel file (Java)

Question

I'm trying to create a file in Java. I have downloaded the lastest Apache POI version and kinda having troubles with all the "build path" thing. I'm not sure if I was doing everything right and not sure what jar files i should use. I try to run the code and thats the error I get:

Error: Unable to initialize main class TestCaused by: java.lang.NoClassDefFoundError: org/apache/poi/ss/usermodel/Workbook

My code:

import java.io.IOException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class Test {
public static void main(String[] args) throws IOException {
    Workbook workbook = new XSSFWorkbook("Test.xlsx");
    Sheet sheet = workbook.createSheet("SheetTest");
    Row headerRow = sheet.createRow(0);
    for (int i = 0; i < 5; i++) {
        Cell cell = headerRow.createCell(i);
        cell.setCellValue(i);
    }
    workbook.close();
}
}

Maybe I have a problem with the classpath? How can I change it? If that's not the problem, Does anyone have an idea?

Answer 1

firstly be sure that you are using the latest version of this library in case you are using maven these dependencies helping you

 <!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->

    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>4.0.1</version>
    </dependency>

    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>4.0.1</version>
    </dependency>

also you have to create a file with .xls or .xlsx extensions you can use something like this

Workbook workbook = WorkbookFactory.create(new File(fileName));

Sheet sheet = workbook.createSheet("sheetName");
int rowIndex = 0;
// this is an example from the official site  iterate over the list  and fill the  sheet 
                while(iterator.hasNext()){
                    Country country = iterator.next();
                    Row row = sheet.createRow(rowIndex++);
                    Cell cell0 = row.createCell(0);
                    cell0.setCellValue(country.getName());
                    Cell cell1 = row.createCell(1);
                    cell1.setCellValue(country.getShortCode());
                }
//lets write the excel data to file now
        FileOutputStream fos = new FileOutputStream(fileName);
        workbook.write(fos);
        fos.close();
        System.out.println(fileName + " written successfully");

Answer 2

Probably, you forgot to add some jar files in the classpath. Try to follow these steps:

1. Right-click on your Project name in Package Explorer tab -> Build Path -> Configure Build Path

2. In "Libraries" tab, remove your old POI library
3. Click on "Add Library" -> User Library -> User Libraries

4. Remove your old libraries and click on "New". Then insert the name of the library and press "ok".
5. Select your new library and click on "Add External Jars".

6. Browse to your extracted POI path and select all the jar files, also in the subfolders!
7. Now click on Apply and close and select the new library on the previous window.

Now it should work!