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How to output large csv file through Apache POI Excel in java?

Struggling to write 300k rows to csv file through Apache POI java. I have been trying to generate a csv file from an excel file with 300k rows. Everytime, I get GCOutMemory error when it tries to write to output csv file. I even tried splitting the write for every 100k rows. The output file size keeps on growing but I don't see system.println statement isnt getting printed.
import javafx.beans.binding.StringBinding;
import org.apache.poi.hssf.record.crypto.Biff8EncryptionKey;
import org.apache.poi.hssf.usermodel.HSSFDateUtil;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.*;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.MemoryType;
import java.math.BigDecimal;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ReadWrite {
private static Logger logger= LoggerFactory.getLogger(ReadWrite.class);
public static void main(String[] args) {
try {
long startReading = System.currentTimeMillis();
Path path = Paths.get("/Users/venkatesh/Documents/Citiout_files/citiout300k_2sheets.xlsx");
byte[] result = new byte[0];
try {
result = Files.readAllBytes(path);
} catch (IOException e) {
e.printStackTrace();
}
InputStream is = new ByteArrayInputStream(result);
Workbook workbook = WorkbookFactory.create(is);
long readDone = System.currentTimeMillis() - startReading;
logger.info("read time " + readDone);
Sheet sheet = workbook.getSheetAt(1);
Row firstRow = sheet.getRow(0);
int headcol = firstRow.getLastCellNum();
long startTransform = System.currentTimeMillis();
firstRow.createCell(headcol++).setCellValue("Sold Amount1");
firstRow.createCell(headcol++).setCellValue("CF_Quantity1");
firstRow.createCell(headcol++).setCellValue("CF_Quantity2");
firstRow.createCell(headcol++).setCellValue("CF_TradePrice");
firstRow.createCell(headcol++).setCellValue("CF_ForwardPrice");
firstRow.createCell(headcol++).setCellValue("CF_UnrealizedPL");
firstRow.createCell(headcol++).setCellValue("CF_Quantity1Round");
firstRow.createCell(headcol++).setCellValue("CF_Quantity2Round");
firstRow.createCell(headcol++).setCellValue("CF_FXLotKeyNoTradeDate");
firstRow.createCell(headcol++).setCellValue("CF_FXRoundedKeyNoTradeDate");
firstRow.createCell(headcol++).setCellValue("CF_SettlementDate");
for (int i = 1; i <=sheet.getLastRowNum()+1; i++) {
String jj="";
Row nRow = sheet.getRow(i-1);
for(Cell c:nRow) {
if (c.getColumnIndex()==3 && i!=1) {
Calendar cal = Calendar.getInstance();
Date date1 = new SimpleDateFormat("dd-MMM-yyyy").parse(c.getStringCellValue());
cal.setTime(date1);
jj = String.valueOf(cal.get(Calendar.MONTH)+1) + "/" + String.valueOf(cal.get(Calendar.DAY_OF_MONTH)) + "/" + String.valueOf(cal.get(Calendar.YEAR));
}
}
int count = nRow.getLastCellNum();
//System.out.println(nRow.getCell(3).getClass());
nRow.createCell(count++).setCellFormula("G" + i + "*-1");
nRow.createCell(count++).setCellFormula("E" + i + "/" + "G" + i);
nRow.createCell(count++).setCellFormula("G" + i + "/E" + i);
nRow.createCell(count++).setCellFormula("ROUND(ABS(T" + i + "/S" + i + "),6)");
nRow.createCell(count++).setCellFormula("ROUND(K" + i + ",6)");
nRow.createCell(count++).setCellFormula("ROUND(N" + i + ",2)");
nRow.createCell(count++).setCellFormula("ROUND(S" + i + ",0)");
nRow.createCell(count++).setCellFormula("ROUND(T" + i + ",0)");
nRow.createCell(count++).setCellFormula("CONCATENATE(T" + i + "," + "\"~\"" + ",S" + i + ")");
nRow.createCell(count++).setCellFormula("CONCATENATE(X" + i + "," + "\"~\"" + ",Y" + i + ")");
nRow.createCell(count++).setCellValue(jj);
c.setCellValue(DateUtil.getExcelDate(calendar.getTime()));
}
long endTransform = System.currentTimeMillis() - startTransform;
System.out.println("Transformations time " + endTransform);
final FormulaEvaluator evaluator = workbook.getCreationHelper().createFormulaEvaluator();
FileWriter writer= new FileWriter(new enter code hereFile("/Users/venkatesh/Documents/cit300k.csv"));
StringBuilder data = new StringBuilder();
Iterator<Row> rowIterator = workbook.getSheetAt(1).iterator();
try {
while (rowIterator.hasNext()) {
Row row = rowIterator.next();
Iterator<Cell> cellIterator = row.cellIterator();
while (cellIterator.hasNext()) {
Cell cell = cellIterator.next();
CellType type = cell.getCellType();
if (type == CellType.BOOLEAN) {
data.append(cell.getBooleanCellValue());
} else if (type == CellType.NUMERIC) {
data.append(cell.getNumericCellValue());
} else if (type == CellType.STRING) {
data.append(cell.getStringCellValue());
} else if (type == CellType.FORMULA) {
switch (evaluator.evaluateFormulaCell(cell)) {
case STRING:
data.append(cell.getStringCellValue());
break;
case NUMERIC:
data.append(cell.getNumericCellValue());
break;
}
} else if (type == CellType.BLANK) {
} else {
data.append(cell + "");
}
data.append(",");
}
writer.append(data.toString());
writer.append('\n');
}
} catch(Exception e){
e.printStackTrace();
}
finally{
if(writer!=null){
writer.flush();
writer.close();
}
}
for (MemoryPoolMXBean mpBean: ManagementFactory.getMemoryPoolMXBeans()) {
if (mpBean.getType() == MemoryType.HEAP) {
System.out.printf(
"Name: %s: %s\n",
mpBean.getName(), mpBean.getUsage()
);
}
}
try {
workbook.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
20-01-12 19:52:49:267 INFO main ReadWrite:64 - read time 11354
Transformations time 38659
Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded
at java.util.TreeMap$Values.iterator(TreeMap.java:1031)
at org.apache.poi.xssf.usermodel.XSSFRow.cellIterator(XSSFRow.java:117)
at org.apache.poi.xssf.usermodel.XSSFRow.iterator(XSSFRow.java:132)
at org.apache.poi.xssf.usermodel.XSSFEvaluationSheet.getCell(XSSFEvaluationSheet.java:86)
at org.apache.poi.ss.formula.WorkbookEvaluator.evaluateFormula(WorkbookEvaluator.java:402)
at org.apache.poi.ss.formula.WorkbookEvaluator.evaluateAny(WorkbookEvaluator.java:275)
at org.apache.poi.ss.formula.WorkbookEvaluator.evaluate(WorkbookEvaluator.java:216)
at org.apache.poi.xssf.usermodel.BaseXSSFFormulaEvaluator.evaluateFormulaCellValue(BaseXSSFFormulaEvaluator.java:56)
at org.apache.poi.ss.formula.BaseFormulaEvaluator.evaluateFormulaCell(BaseFormulaEvaluator.java:185)
at ReadWrite.main(ReadWrite.java:150)

So now that we have a usable stacktrace, it is clear that the problem is NOT happening while writing the CSV file. It is actually happening while you are evaluating a spreadsheet formula. My guess is that the formula is summing across all rows in a sheet ... or something like that.
This is a problem, and there is probably no simple solution.
Here's what the POI documentation says:
File sizes/Memory usage
There are some inherent limits in the Excel file formats. These are defined in class SpreadsheetVersion. As long as you have enough
main-memory, you should be able to handle files up to these limits.
For huge files using the default POI classes you will likely need a
very large amount of memory.
There are ways to overcome the main-memory limitations if needed:
For writing very huge files, there is SXSSFWorkbook which allows to do a streaming write of data out to files (with certain
limitations on what you can do as only parts of the file are held in
memory).
For reading very huge files, take a look at the sample XLSX2CSV which shows how you can read a file in streaming
fashion (again with some limitations on what information you can read
out of the file, but there are ways to get at most of it if
necessary).
You are clearly running into these memory limitations. Basically, POI is trying to load too much of the spreadsheet into memory ... while you are evaluating the spreadsheet formulae ... and you are filling the heap.
One solution would be to increase the Java heap size. Or if you are already using all available RAM for your heap, run the conversion on a machine with more RAM. A lot of standard PCs have 16GB RAM these days. Maybe it is time for a hardware upgrade? But I'm guessing you have already thought of this.
If increasing the heap size is not viable, then you will need to rewrite your application to use SXSSFWorkbook. Furthermore, you may need to replace your approach of using formula evaluation with doing the calculations in native Java in a way that is compatible with row-by-row streaming of the spreadsheet. (It will depend on what the formulae do.)
Look at the linked example from the POI documentation for ideas.

How to get pictures with names from an xls file using Apache POI

Using workbook.getAllPictures() I can get an array of picture data but unfortunately it is only the data and those objects have no methods for accessing the name of the picture or any other related information.
There is a HSSFPicture class which would contain all the details of the picture but how to get for example an array of those objects from the xls?
Update:
Found SO question How can I find a cell, which contain a picture in apache poi which has a method for looping through all the pictures in the worksheet. That works.
Now that I was able to try the HSSFPicture class I found out that the getFileName() method is returning the file name without the extension. I can use the getPictureData().suggestFileExtension() to get a suggested file extension but I really would need to get the extension the picture had when it was added into the xls file. Would there be a way to get it?
Update 2:
The pictures are added into the xls with a macro. This is the part of macro that is adding the images into the sheet. fname is the full path and imageName is the file name, both are including the extension.
Set img = Sheets("Receipt images").Pictures.Insert(fname)
img.Left = 10
img.top = top + 10
img.Name = imageName
Set img = Nothing
The routine to check if the picture already exists in the Excel file.
For Each img In Sheets("Receipt images").Shapes
If img.Name = imageName Then
Set foundImage = img
Exit For
End If
Next
This recognizes that "image.jpg" is different from "image.gif", so the img.Name includes the extension.

The shape names are not in the default POI objects. So if we need them we have to deal with the underlying objects. That is for the shapes in HSSF mainly the EscherAggregate (http://poi.apache.org/apidocs/org/apache/poi/hssf/record/EscherAggregate.html) which we can get from the sheet. From its parent class AbstractEscherHolderRecord we can get all EscherOptRecords which contains the options of the shapes. In those options are also to find the groupshape.shapenames.
My example is not the complete solution. It is only provided to show which objects could be used to achieve this.
Example:
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.InputStream;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.hssf.record.*;
import org.apache.poi.ddf.*;
import java.util.List;
import java.util.ArrayList;
class ShapeNameTestHSSF {
public static void main(String[] args) {
try {
InputStream inp = new FileInputStream("workbook1.xls");
Workbook wb = WorkbookFactory.create(inp);
Sheet sheet = wb.getSheetAt(0);
EscherAggregate escherAggregate = ((HSSFSheet)sheet).getDrawingEscherAggregate();
EscherContainerRecord escherContainer = escherAggregate.getEscherContainer().getChildContainers().get(0);
//throws java.lang.NullPointerException if no Container present
List<EscherRecord> escherOptRecords = new ArrayList<EscherRecord>();
escherContainer.getRecordsById(EscherOptRecord.RECORD_ID, escherOptRecords);
for (EscherRecord escherOptRecord : escherOptRecords) {
for (EscherProperty escherProperty : ((EscherOptRecord)escherOptRecord).getEscherProperties()) {
System.out.println(escherProperty.getName());
if (escherProperty.isComplex()) {
System.out.println(new String(((EscherComplexProperty)escherProperty).getComplexData(), "UTF-16LE"));
} else {
if (escherProperty.isBlipId()) System.out.print("BlipId = ImageId = ");
System.out.println(((EscherSimpleProperty)escherProperty).getPropertyValue());
}
System.out.println("=============================");
}
System.out.println(":::::::::::::::::::::::::::::");
}
FileOutputStream fileOut = new FileOutputStream("workbook1.xls");
wb.write(fileOut);
fileOut.flush();
fileOut.close();
} catch (InvalidFormatException ifex) {
} catch (FileNotFoundException fnfex) {
} catch (IOException ioex) {
}
}
}
Again: This is not a ready to use solution. A ready to use solution cannot be provided here, because of the complexity of the EscherRecords. Maybe to get the correct EscherRecords for the image shapes and their related EscherOptRecords, you have recursive to loop through all EscherRecords in the EscherAggregate checking whether they are ContainerRecords and if so loop through its children and so on.

Start here:
http://poi.apache.org/spreadsheet/quick-guide.html#Images
this tutorial can help you to extract an image's information from an xls spreadsheet using Apache POI

Using hashmap for POI Java XLSX

I have been trying to edit my code to allow a XLSX file to be uploaded and be able to be read on the website. But after countless tries, the data I typed into the XLSX File is unable to be captured on the website. (Eg: After downloading the XLSX Template from the website, I am able to type in anything that I want in the XLSX file and able to upload it again to the website so I do not need to keep on adding new data by clicking "new" every single time. I can just type in everything in that XLSX File all at once and upload it right away)
I was told to use hashmap but I am unsure of the way it works. The codes I have currently only enables the website to capture the header title and I am not suppose to use jxl.
While removing those codes that has jxl, I encounter some errors (being underline in red).
public HashMap getConstructJXLList_xlsx(UploadedFile File, int Sheetindex) {
String _LOC = "[PageCodeBase: getConstructJXLList]";
HashMap _m = new HashMap();
InputStream _is = null;
try {
_is = File.getInputstream();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
XSSFWorkbook workbook;
XSSFSheet s;
try {
workbook = new XSSFWorkbook(_is);
s = workbook.getSheetAt(Sheetindex);
} catch (Exception e) {
System.out.println(_LOC + "1.0 " + " Test:");
int _totalc = getColumns(); //getColumns is being underline in red
int _totalr = getRows(); //getRows is being underline in red
// Header r=0
String[] _st = new String[_totalc];
//XSSFSheet sheet = null;
for (int _c = 0; _c < _totalc; _c++) {
_st[_c] = getCell(_c, 0); //getCell is being underline in red
}
_m.put("HEADER", _st);
System.out.println(_LOC + "1.0 " + " _m:" + _m);
// Data r=1 thereafter
List _l = new ArrayList();
for (int _r = 1; _r < _totalr; _r++) {
Object[] _o = new Object[_totalc];
String _s_r = null;
for (int _c = 0; _c < _totalc; _c++) {
_o[_c] = getCell(_c, _r);
String _cn = _o[_c].getClass().getName();
String _s_c = null;
if (!isEmptyNull(_s_c)) {
_s_r = "record_available";
}
}
if ((_o != null) && (_o.length != 0)) {
_l.add(_o);
}
}
_m.put("DATA", _l);
System.out.println(_LOC + "1.0 " + " _m:" + _m);
}
return _m;
}
Do you mind helping me to solve this? Why there isn't any data being capture in the website? The error shown is "The method getColumns/getCell/getRows is undefined for the type PageCodeBase." And the help/quick fix given is to create a new method. But after creating the new method, I am unsure of what to add in the methods. Have tried various example (http://snippetjournal.wordpress.com/2014/02/05/read-xlsx-using-poi/) but I stil can't seem to get it work out.

I would recommend you to manage de excel file using this classes from the apache POI api
org.apache.poi.ss.usermodel.Cell;
org.apache.poi.ss.usermodel.Row;
org.apache.poi.ss.usermodel.Sheet;
org.apache.poi.ss.usermodel.Workbook;
org.apache.poi.ss.usermodel.WorkbookFactory;
instead of those XSSFWorkbook, XSSFSheet...
And also when accessing the file input stream try doing it this way:
FileInputStream input = new FileInputStream(new File("C:\\Users\\admin\\Desktop\\Load_AcctCntr_Template.xlsx"));
Workbook workBook = WorkbookFactory.create(stream);
workBook.getSheetAt(0);

use this.
FileInputStream input = new FileInputStream(new File("C:/Users/admin/Desktop/Load_AcctCntr_Template.xlsx"));
Workbook wb = WorkbookFactory.create(input);
as mentioned in user3661357 answer. use
Workbook instead of XSSFWorkbook.
Sheet instead of XSSFSheet.
etc..
Also read this
Getting Exception(org.apache.poi.openxml4j.exception - no content type [M1.13]) when reading xlsx file using Apache POI?
*HINT > use ALT+SHIFT+I in netbeans to load the necessary packages.
A working example
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
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.ss.usermodel.WorkbookFactory;
public class POITest {
public static void test() {
try {
FileInputStream input = new FileInputStream(new File("C:/Users/kingslayer/Desktop/test/a.xlsx"));
Workbook wb = WorkbookFactory.create(input);
Sheet s = wb.getSheetAt(0);
Iterator<Row> rows = s.rowIterator();
while (rows.hasNext()) {
Row row = rows.next();
Iterator cells = row.cellIterator();
while (cells.hasNext()) {
Cell cell = (Cell) cells.next();
if (cell.getCellType() == Cell.CELL_TYPE_STRING) {
System.out.print(cell.getStringCellValue() + "t");
} else if (cell.getCellType() == Cell.CELL_TYPE_NUMERIC) {
System.out.print(cell.getNumericCellValue() + "t");
} else if (cell.CELL_TYPE_BLANK == cell.getCellType()) {
System.out.print("BLANK ");
} else {
System.out.print("Unknown cell type");
}
}
input.close();
}
} catch (IOException | InvalidFormatException ex) {
Logger.getLogger(POITest.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args) {
test();
}
}
All the libraries you must have on the project path.
commons-codec-1.5.jar ,
commons-logging-1.1.jar ,
dom4j-1.6.1.jar ,
junit-3.8.1.jar ,
log4j-1.2.13.jar ,
poi-3.9-20121203.jar ,
poi-excelant-3.9-20121203.jar ,
poi-ooxml-3.9-20121203.jar ,
poi-ooxml-schemas-3.9-20121203.jar ,
poi-scratchpad-3.9-20121203.jar ,
stax-api-1.0.1.jar ,
xmlbeans-2.3.0.jar ,

1) get rid of POIFSFileSystem fs = new POIFSFileSystem(input); as you are not using it
2) input.close(); is called after first iteration of row

Parse Excel data in Java effectivley

I'm supposed to realize a Java application that should retrieve data out of an excel spreadsheet and link it to some objects I've already created in order to apply some calculations on them, then display the result .
About the app
==> The excel spreadsheet is a survey to measure a bank's clients satisfaction about the bank's services.
==> The application should parse the data in the spreadsheet, and do some calculations on it.
==> The result should be displayed using an interactive GUI .
What I've done so far
I've analysed to problem and create all the objects I will need in my application.
I Actually did some search here on stackoverflow.com and think that Apache POI would be very useful.
Where I need help
The problem is that I have no idea about what I should begin with .
Any suggestions on how to accomplish this , what tools, languages, API or design pattern I should use is more than welcome.

I disagree with your choice of POI. I think Andy Khan's JExcel is far superior.
I'd wonder why an Excel spreadsheet and not a relational database.
This sounds like a standard layered web application. The best advice is to break the problem into pieces:
Acquire the data
Perform the calculations
Write the UI to display them.
Get each piece working and tested separately, then put it aside. Work your way through the layers, one by one.

you might already be having the apache POI library , this might help you get started on source code basis
import java.io.*;
import java.util.Iterator;
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 ReadExcelFile {
public static void main(String[] args)
{
try {
FileInputStream file = new FileInputStream(new File("C:/Users/hussain.a/Desktop/mar_25/Tradestation_Q4 Dashboard_Week 5_1029-1104.xlsx"));
XSSFWorkbook workbook = new XSSFWorkbook(file);
XSSFSheet sheet = workbook.getSheetAt(0);
Iterator<Row> rowIterator = sheet.iterator();
rowIterator.next();
while(rowIterator.hasNext())
{
Row row = rowIterator.next();
//For each row, iterate through each columns
Iterator<Cell> cellIterator = row.cellIterator();
while(cellIterator.hasNext())
{
Cell cell = cellIterator.next();
switch(cell.getCellType())
{
case Cell.CELL_TYPE_BOOLEAN:
System.out.println("boolean===>>>"+cell.getBooleanCellValue() + "\t");
break;
case Cell.CELL_TYPE_NUMERIC:
System.out.println("numeric===>>>"+cell.getNumericCellValue() + "\t");
break;
case Cell.CELL_TYPE_STRING:
System.out.println("String===>>>"+cell.getStringCellValue() + "\t");
break;
}
}
System.out.println("");
}
file.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}

Convert .csv to .xls in Java

Does anyone here know of any quick, clean way to convert csv files to xls or xlsx files in java?
I have something to manage csv files already in place and I need the extra compatibility for other programs.
Sample code in addition to package names is always well appreciated.
Many thanks,
Justian
Here's my code thus far. I need to remove the returns ("\n") from the lines. Some of my cells contain multiple lines of information (a list), so I can use "\n" in csv to indicate multiple lines within a cell, but xls treats these as if I mean to put them on a new line.
The code is modified from the internet and a little messy at the moment. You might notice some deprecated methods, as it was written in 2004, and be sure to ignore the terrible return statements. I'm just using S.o.p at the moment for testing and I'll clean that up later.
package jab.jm.io;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
public class FileConverter {
public static String ConvertCSVToXLS(String file) throws IOException {
if (file.indexOf(".csv") < 0)
return "Error converting file: .csv file not given.";
String name = FileManager.getFileNameFromPath(file, false);
ArrayList<ArrayList<String>> arList = new ArrayList<ArrayList<String>>();
ArrayList<String> al = null;
String thisLine;
DataInputStream myInput = new DataInputStream(new FileInputStream(file));
while ((thisLine = myInput.readLine()) != null) {
al = new ArrayList<String>();
String strar[] = thisLine.split(",");
for (int j = 0; j < strar.length; j++) {
// My Attempt (BELOW)
String edit = strar[j].replace('\n', ' ');
al.add(edit);
}
arList.add(al);
System.out.println();
}
try {
HSSFWorkbook hwb = new HSSFWorkbook();
HSSFSheet sheet = hwb.createSheet("new sheet");
for (int k = 0; k < arList.size(); k++) {
ArrayList<String> ardata = (ArrayList<String>) arList.get(k);
HSSFRow row = sheet.createRow((short) 0 + k);
for (int p = 0; p < ardata.size(); p++) {
System.out.print(ardata.get(p));
HSSFCell cell = row.createCell((short) p);
cell.setCellValue(ardata.get(p).toString());
}
}
FileOutputStream fileOut = new FileOutputStream(
FileManager.getCleanPath() + "/converted files/" + name
+ ".xls");
hwb.write(fileOut);
fileOut.close();
System.out.println(name + ".xls has been generated");
} catch (Exception ex) {
}
return "";
}
}

Don't know if you know this already, but:
Excel (if that's your real target) is easily able to read .csv files directly, so any conversion you'd do would only be a courtesy to your less "gifted" users.
CSV is a lowest-common-denominator format. It's unlikely for any converter to add information to that found in a .csv file that will make it more useful. In other words, CSV is a "dumb" format and converting it to .xls will (probably) increase file size but not make the format any smarter.
Curtis' suggestion of POI is the first thing that would come to my mind too.
If you're doing this conversion on a Windows machine, another alternative could be Jacob, a Java-COM bridge that would allow you to effectively remote control Excel from a Java program so as to do things like open a file and save in a different format, perhaps even applying some formatting changes or such.
Finally, I've also had some success doing SQL INSERTs (via JDBC) into an Excel worksheet accessed via the JDBC-ODBC bridge. i.e. ODBC can make an Excel file look like a database. It's not very flexible though, you can't ask the DB to create arbitrarily named .XLS files.
EDIT:
It looks to me like readLine() is already not giving you whole lines. How is it to know that carriage return is not a line terminator? You should be able to verify this with debug print statements right after the readLine().
If this is indeed so, it would suck because the way forward would be for you to
either recognize incomplete lines and paste them together after the fact,
or write your own substitute for readLine(). A simple approach would be to read character by character, replacing CRs within a CSV string and accumulating text in a StringBuilder until you feel you have a complete line.
Both alternatives are work you probably weren't looking forward to.

If you want to read or write XLS or XLSX files in Java, Apache POI is a good bet: http://poi.apache.org/

Copy paste the below program,I ran the program and it is working fine,Let me know if you have any concerns on this program.(You need Apache POI Jar to run this program)
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
public class CSVToExcelConverter {
public static void main(String args[]) throws IOException
{
ArrayList arList=null;
ArrayList al=null;
String fName = "test.csv";
String thisLine;
int count=0;
FileInputStream fis = new FileInputStream(fName);
DataInputStream myInput = new DataInputStream(fis);
int i=0;
arList = new ArrayList();
while ((thisLine = myInput.readLine()) != null)
{
al = new ArrayList();
String strar[] = thisLine.split(",");
for(int j=0;j<strar.length;j++)
{
al.add(strar[j]);
}
arList.add(al);
System.out.println();
i++;
}
try
{
HSSFWorkbook hwb = new HSSFWorkbook();
HSSFSheet sheet = hwb.createSheet("new sheet");
for(int k=0;k<arList.size();k++)
{
ArrayList ardata = (ArrayList)arList.get(k);
HSSFRow row = sheet.createRow((short) 0+k);
for(int p=0;p<ardata.size();p++)
{
HSSFCell cell = row.createCell((short) p);
String data = ardata.get(p).toString();
if(data.startsWith("=")){
cell.setCellType(Cell.CELL_TYPE_STRING);
data=data.replaceAll("\"", "");
data=data.replaceAll("=", "");
cell.setCellValue(data);
}else if(data.startsWith("\"")){
data=data.replaceAll("\"", "");
cell.setCellType(Cell.CELL_TYPE_STRING);
cell.setCellValue(data);
}else{
data=data.replaceAll("\"", "");
cell.setCellType(Cell.CELL_TYPE_NUMERIC);
cell.setCellValue(data);
}
//*/
// cell.setCellValue(ardata.get(p).toString());
}
System.out.println();
}
FileOutputStream fileOut = new FileOutputStream("test.xls");
hwb.write(fileOut);
fileOut.close();
System.out.println("Your excel file has been generated");
} catch ( Exception ex ) {
ex.printStackTrace();
} //main method ends
}
}

The tools in Excel are not adequate for what the OP wants to do. He's on the right track there. Excel cannot import multiple CSV files into different worksheets in the same file, which is why you'd want to do it in code. My suggestion is to use OpenCSV to read the CSV, as it can automatically correct for newlines in data and missing columns, and it's free and open source. It's actually very, very robust and can handle all sorts of different non-standard CSV files.

You wrote:
I have something to manage csv files
already in place and I need the extra
compatibility for other programs.
What are those other programs? Are they required to access your data through Excel files, or could they work with an JDBC or ODBC connection to a database? Using a database as the central location, you could extract the data into CSV files or other formats as needed.

I created a small software called csv2xls. It needs Java.