How to speed up autosizing columns in apache POI?

Question

I use the following code in order to autosize columns in my spreadsheet:

for (int i = 0; i < columns.size(); i++) {
   sheet.autoSizeColumn(i, true);
   s         


        

Answer 1

The autoSizeColumn function itself works not perfect and some columns width not exactly fit the data inside. So, I found some solution that works for me.

1. To avoid crazy calculations let give that to autoSizeColumn() function:

   sheet.autoSizeColumn();

2. Now, our column autosized by library but we wont to add a little bit more to the current column width to make table looks fine:

   // get autosized column width
   int currentColumnWidth = sheet.getColumnWidth();

   // add custom value to the current width and apply it to column
   sheet.setColumnWidth(, (currentColumnWidth + 2500));

3. The full function could looks like:

   public void autoSizeColumns(Workbook workbook) {
        int numberOfSheets = workbook.getNumberOfSheets();
        for (int i = 0; i < numberOfSheets; i++) {
            Sheet sheet = workbook.getSheetAt(i);
            if (sheet.getPhysicalNumberOfRows() > 0) {
                Row row = sheet.getRow(sheet.getFirstRowNum());
                Iterator cellIterator = row.cellIterator();
                while (cellIterator.hasNext()) {
                    Cell cell = cellIterator.next();
                    int columnIndex = cell.getColumnIndex();
                    sheet.autoSizeColumn(columnIndex);
                    int currentColumnWidth = sheet.getColumnWidth(columnIndex);
                    sheet.setColumnWidth(columnIndex, (currentColumnWidth + 2500));
                }
            }
        }
    }

P.S. Thanks Ondrej Kvasnovsky for the function https://stackoverflow.com/a/35324693/13087091