如何以英寸为单位设置固定的列宽值。 Apache POI

Question

Im setting fixed widths for the columns for the excel im creating with Apache POI. Im having the fixed values in inches. So I want to know what is the measurement that Apcahe POI is taking as a parameter. And how can I call it using the values in inches?

Sheet sheet; sheet.setColumnWidth(0, 100);

Answer 1

In Sheet.setColumnWidth is told that the measurement unit here is 1/256th of a character width. It also is told how exactly Excel calculates this.

So if one wants Excel shall show column width as 10, using default font Calibri 11, then the width256 must be calculated as (int)Math.round((10*Units.DEFAULT_CHARACTER_WIDTH+5f)/Units.DEFAULT_CHARACTER_WIDTH*256f) .

If the need is setting the column width in inches, then first the inches should be translated to pixels and then the width256 must be calculated as (int)Math.round(widthPx/Units.DEFAULT_CHARACTER_WIDTH*256f) .

There is Units as a helper class for unit management.

Example:

import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.util.Units;

class ExcelSetColumnWidth {

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

  try (Workbook workbook = new XSSFWorkbook(); 
       FileOutputStream fileout = new FileOutputStream("Excel.xlsx") ) {
   Sheet sheet = workbook.createSheet();
   int widthExcel = 10;
   int width256 = (int)Math.round((widthExcel*Units.DEFAULT_CHARACTER_WIDTH+5f)/Units.DEFAULT_CHARACTER_WIDTH*256f);
   System.out.println(width256);
   sheet.setColumnWidth(0, width256);
   sheet.createRow(0).createCell(0).setCellValue("1234567890"); // Excel shows column width as 10 using default font Calibri 11

   float widthInch = 1f;
   float widthPx = widthInch * Units.PIXEL_DPI;
   width256 = (int)Math.round(widthPx/Units.DEFAULT_CHARACTER_WIDTH*256f);
   System.out.println(width256);
   sheet.setColumnWidth(1, width256);
   System.out.println(sheet.getColumnWidthInPixels(1)); // should be round 96 pixels for an inch
   sheet.createRow(1).createCell(1).setCellValue("1 inch width"); // column is 1 inch width

   workbook.write(fileout);
  }

 }
}