Hi,

this bug seems to be similar to bug 42920 (Excel Comments).

When attaching comments to a cell with poi-3.0.1-FINAL-20070705.jar and the
comments exceed a size of 4111 characters, the file can't be loaded by Excel any
more (I tried Excel 2003 and Excel 2007).

There are no problems in saving the file. However, when opening the file with
Excel, I get the error message "Excel found unreadable content in foo.xls".

Attached a small test case which reproduces the problem. The created excel file
works fine if the comment size is up to 4111 characters. But with a comment size
of 4112 characters, the excel file can't be loaded any more.

import java.io.FileOutputStream;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFClientAnchor;
import org.apache.poi.hssf.usermodel.HSSFComment;
import org.apache.poi.hssf.usermodel.HSSFPatriarch;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class Comments {

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

        HSSFWorkbook workBook = new HSSFWorkbook();
        HSSFSheet sheet = workBook.createSheet();
        HSSFPatriarch patriarch = sheet.createDrawingPatriarch();
        
        HSSFRow row = sheet.createRow(0);
        HSSFCell cell = row.createCell((short)0);

        // works  with 4111
        // broken with 4112
        int size = 4112;
        
        StringBuffer toolTip = new StringBuffer(size);
        for (int i = 0; i < size; i++) {
            toolTip.append(".");
        }
        
        HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0, 0, 0, (short)0, 0,
(short)1, 1);
        HSSFComment comment = patriarch.createComment(anchor);
        comment.setString(new HSSFRichTextString(toolTip.toString()));
        cell.setCellComment(comment);
        
        workBook.write(new FileOutputStream("foo.xls"));
    }
}

Regards,
Jan