Apache POI Word support - workaround for a write bug

Question

Hi all,
Just finished battling with the bugs in POI HWPF component. When searching forums, I found more questions than answers so I wanted to save others a significant effort until POI guys implement all the fixes.
Basically, the synopsis is, all the delete() methods are broken and replacing a string with a string of a different size corrupts the document. But insertAfter and insertBefore methods are mostly working.
I did not want to add a method to their class, because it will probably be overwritten. On the other hand, it is unknown when it will be fixed. Therefore, I had to go via reflection.
Here's the method, just attach it to your class and it's ready to use:
      * Replaces text in the paragraph by a specified new text.
      * @param r     A paragraph to replace.
      * @param newText     A new text.
      * @throws Exception     if anything goes wrong
     protected void setParagraphText(Paragraph r, String newText) throws Exception {
          int length = r.text().length() - 1;
          Class clRange = Range.class;
          Field fldText = clRange.getDeclaredField("_text");
          fldText.setAccessible(true);
          Field fldTextEnd = clRange.getDeclaredField("_textEnd");
          fldTextEnd.setAccessible(true);
          Field fldStart = clRange.getDeclaredField("_start");
          fldStart.setAccessible(true);
          List textPieces = (List)fldText.get(r);
          int _textEnd = fldTextEnd.getInt(r);
          TextPiece t = (TextPiece)textPieces.get(_textEnd - 1);
          StringBuffer sb = t.getStringBuffer();
          int offset = fldStart.getInt(r);
          int diff = newText.length() - length;
          if (diff <= 0) {
               // delete doesn't work properly yet, corrupting the documents.
               // Therefore a quick and ugly workaround is to pad the new text with spaces
               for (int i = 0; i < -diff; i++)
                    newText += " ";
               sb.replace(offset, offset + length, newText);
          } else {
               // when the new text is longer, the old one must be replaced
               // character by character, and the difference is added using
               // insertAfter method
               if (r.isInTable()) {
                    // more obstacles when working with tables though.
                    // Not only the regular insertAfter does not work,
                    // but also insertAfter called from a cell overruns cell delimiters.
                    // Needless to say, getTable(r) does not return the required table.
                    // Fortunately, there's a workaround
                    TableIterator ti = new TableIterator(range);
                    TableCell tc;
                    while (ti.hasNext()) {
                         Table tbl = ti.next();
                         for (int i = 0; i < tbl.numRows(); i++) {
                              TableRow tr = tbl.getRow(i);
                              for (int j = 0; j < tr.numCells(); j++) {
                                   tc = tr.getCell(j);
                                   if (tc.text().startsWith(sb.substring(offset, offset + length))) {
                                        sb.replace(offset, offset + length,
                                                  newText.substring(newText.length() - length));
                                        // only like this, otherwise cell delimiter will be run over
                                        tc.insertBefore(newText.substring(0, newText.length() - length));
                                        return;
                    sb.replace(offset, offset + length, newText.substring(0, length));
               } else {
                    sb.replace(offset, offset + length, newText.substring(0, length));
                    r.insertAfter(newText.substring(length));
     }

Answer 1

user8984775 wrote:
My requirement is I need to apply this formula for Entire column to achieve the need like
When user enters data in col2 (B) of greater than the number specified in col1 (A) and then show the ErrorBox.
I am able to get the formula working through code only for first cell as per below code... I want it to dynamically apply for the entire column. Well I'm certainly no expert on POI, but that looks like a very odd formula to me.
When you "pull" a formula down a column, Excel automatically changes the formula for each row, but because you've fixed both the column AND the row ($A$1), it'll be the same in all cases.
I don't know if POI allows that sort of "auto-generate" for formulas, but if so try something like $A1 instead; otherwise I suspect you'll need a different formula for each row.
Winston