The default JVM heap size is very small. You either need to increase it to a more sensible size, or if you really are constrained to a tiny heap, switch to SAX based parsing (as detailed on the website)

But when I use the SAX parser , it can't take null valued cell..

If you're not sure how to use the SAX parser, ask on the user list. If you've found a bug in the SAX parser, please raise a new bugzilla entry for that. As it stands, you just need to either increase your heap size to something sensible, or use SAX

Am using this code...But it cannot[Neglect] empty cell... Is there any idea to get null cell in the following code ???

....void parseExcel(File file) throws IOException 
	{
		
  OPCPackage container;
        try 
		{
            container = OPCPackage.open(file.getAbsolutePath());
            ReadOnlySharedStringsTable strings = new ReadOnlySharedStringsTable(container);
            XSSFReader xssfReader = new XSSFReader(container);
            StylesTable styles = xssfReader.getStylesTable();
            XSSFReader.SheetIterator iter = (XSSFReader.SheetIterator) xssfReader.getSheetsData();
			
            while (iter.hasNext()) 
			{
				
                InputStream stream = iter.next();
				processSheet(styles, strings, stream);
                stream.close();
				
            }


	protected static void processSheet(StylesTable styles, ReadOnlySharedStringsTable strings, InputStream sheetInputStream) throws IOException, SAXException 
	{
				
        InputSource sheetSource = new InputSource(sheetInputStream);
        SAXParserFactory saxFactory = SAXParserFactory.newInstance();
        try 
		{
            SAXParser saxParser = saxFactory.newSAXParser();
            XMLReader sheetParser = saxParser.getXMLReader();
            ContentHandler handler = new XSSFSheetXMLHandler(styles, strings, new SheetContentsHandler() 
			{
				
				@Override
                public void startRow(int rowNum) 
				{
					//System.out.println("")
					
				}
                @Override
                public void endRow() 
				{
                	stringList.add("Row");
                }
                @Override
                public void cell(String cellReference, String formattedValue) 
				{
					System.out.println(formattedValue);
				}
                @Override
                public void headerFooter(String text, boolean isHeader, String tagName) 
				{
                	System.out.println(isHeader?"Header " +text:"Footer "+text );
                }

            }, 
            false//means result instead of formula
            );
            sheetParser.setContentHandler(handler);
            sheetParser.parse(sheetSource);
        } 
		catch 
		{

My previous comment still stands:

If you're not sure how to use the SAX parser, ask on the user list. If you've found a bug in the SAX parser, please raise a new bugzilla entry for that.For *this* bug, you just need to either increase your heap size to something sensible, or use SAX properly