Java heap space issue while creating Apache poi Workbook - csv

Question

I am trying to convert a large xlsx sheet to csv using the example given here and here . But it is throwing the below error on line
XSSFWorkbook wBook = new XSSFWorkbook(new FileInputStream(file));
Error
Caught throwable Java heap space
java.lang.OutOfMemoryError: Java heap space
at java.io.ByteArrayOutputStream.<init>(ByteArrayOutputStream.java:77)
Is there any efficient way to convert large xlsx sheet to csv without increasing heap memory?
My code is as below-
try
{
// Get the workbook object for XLSX file
// XSSFWorkbook wBook = new XSSFWorkbook(new FileInputStream(file));
XSSFWorkbook wBook = new XSSFWorkbook(new FileInputStream(file));
for(int i=0;i<wBook.getNumberOfSheets();i++)
{
XSSFSheet sheet = wBook.getSheetAt(i);
fileName = convertedFileLocation + sheet.getSheetName() + ".csv";
FileOutputStream fos = new FileOutputStream(fileName);
//System.out.println(wBook.getSheetAt(i).getSheetName());
Row row;
Cell cell;
// Iterate through each rows from first sheet
Iterator<Row> rowIterator = sheet.iterator();
while (rowIterator.hasNext())
{
row = rowIterator.next();
// For each row, iterate through each columns
Iterator<Cell> cellIterator = row.cellIterator();
while (cellIterator.hasNext())
{
cell = cellIterator.next();
data.append("\"" + cell.getStringCellValue() + "\",\r\n");
}
}
fos.write(data.toString().getBytes());
fos.close();
}
wBook.close();
}
Edited---
I am using XSSF as suggested by #axel and #gagravarr in the comment and using the class method as below. Though it is creating the converted.csv file the csv file is empty. Any idea what I am doing wrong
private boolean convertToCSV2(File file)
{
try {
OPCPackage p = OPCPackage.open(file.getPath());
String convertedFileLocation = siteConfigService.getProperty(CONVERTEDFOLDER);
String convertedFileName = convertedFileLocation+"converted.csv";
PrintStream pout=new PrintStream(convertedFileName);
XLSX2CSV xlsToCSV = new XLSX2CSV(p, pout, -1);
} catch (InvalidFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return true;
}