[java] Merging cells in Excel using Apache POI

You can use :

sheet.addMergedRegion(new CellRangeAddress(startRowIndx, endRowIndx, startColIndx,endColIndx));

Make sure the CellRangeAddress does not coincide with other merged regions as that will throw an exception.

• If you want to merge cells one above another, keep column indexes same
• If you want to merge cells which are in a single row, keep the row indexes same
• Indexes are zero based

For what you were trying to do this should work:

sheet.addMergedRegion(new CellRangeAddress(rowNo, rowNo, 0, 3));