apache poi excel大自动列宽

Question

I am try to create a big excel 2010 with 30 columns and 1 million records with Apache poi latest. I am creating as describe in this link http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/BigGridDemo.java . but I want column width to be same as column header text size. but when I am doing this after creating excel with following code

for (int x = 0; x < sheet.getRow(0).getPhysicalNumberOfCells(); x++) {
            sheet.setColumnWidth(x, 20*256);
        }

it is taking a huge time and even with 5gb heap size I am getting out of memory.

thanks

ram

Answer 1

First Select the first row or header because only Header can give you the max number of cells in a row.

HSSFRow row = wb.getSheetAt(0).getRow(0);

Then use autoSizeColumn on each column of that row

for(int colNum = 0; colNum<row.getLastCellNum();colNum++)   
    wb.getSheetAt(0).autoSizeColumn(colNum);

This will set the column width same as that of its Header width.

Answer 2

I would also suggest you look at using sxssf. It uses an xml format to load it into Excel. This is much faster and a better way to create large reports or grids. The autosizing function in xssf takes too long by default.

Answer 3

sheet.autoSizeColumn(columnNumber) works. this will resize the column to the largest cell length.