Create Excel file in java using PoI

package com.howto;

import java.io.File;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;

/*
 * Here we will learn how to create Excel file and header for the same.
 */
public class CreateExcelFile {

	int rownum = 0;
	HSSFSheet firstSheet;
	Collection<File> files;
	HSSFWorkbook workbook;
	File exactFile;

	{
		workbook = new HSSFWorkbook();
		firstSheet = workbook.createSheet("FIRST SHEET");
		Row headerRow = firstSheet.createRow(rownum);
		headerRow.setHeightInPoints(40);
	}

	public static void main(String args[]) throws Exception {

		List<String> headerRow = new ArrayList<String>();
		headerRow.add("Employee No");
		headerRow.add("Employee Name");
		headerRow.add("Employee Address");

		List<String> firstRow = new ArrayList<String>();
		firstRow.add("1111");
		firstRow.add("Gautam");
		firstRow.add("India");

		List<List> recordToAdd = new ArrayList<List>();
		recordToAdd.add(headerRow);
		recordToAdd.add(firstRow);

		CreateExcelFile cls = new CreateExcelFile(recordToAdd);
		cls.createExcelFile();
	}

	void createExcelFile(){
		FileOutputStream fos = null;
		try {
			fos=new FileOutputStream(new File("ExcelSheet.xls"));
			HSSFCellStyle hsfstyle=workbook.createCellStyle();
			hsfstyle.setBorderBottom((short) 1);
			hsfstyle.setFillBackgroundColor((short)245);
			workbook.write(fos);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	 CreateExcelFile(List<List> l1) throws Exception {

		try {

			for (int j = 0; j < l1.size(); j++) {
				Row row = firstSheet.createRow(rownum);
				List<String> l2= l1.get(j);

				for(int k=0; k<l2.size(); k++)
				{
					Cell cell = row.createCell(k);
					cell.setCellValue(l2.get(k));
				}
				rownum++;
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
		}

	}
}

PoI Jar will be required. Jar can be downloaded from Apache website.