Apache POI Double Values in ComboBox

问题:

I want to have a ComboBox with the following entrys:

{"0,5", "1", "1,5", "2", "2,5"}

I use DataValidation:

    DataValidation dataValidation = null;
    DataValidationConstraint constraint = null;
    DataValidationHelper validationHelper = null;

    validationHelper = new XSSFDataValidationHelper(sheet);
    CellRangeAddressList addressList = new  CellRangeAddressList(row, row, col, col);
    constraint = validationHelper.createExplicitListConstraint(list);
    dataValidation = validationHelper.createValidation(constraint, addressList);
    dataValidation.setSuppressDropDownArrow(true);   
    sheet.addValidationData(dataValidation);

The list is of the following structure:

list = new String[]{ "0,5", "1", "1,5", "2", "2,5" }

But after generating the excel file, something else is in the dropdown list.

0, 5, 1, 1, 5

Why is that?

If I use a point notation (0.5, 1, 1.5) the next problem is, when I choose from the ComboBox, excel autoformat its to a date, e.g 1.5 -> 01. May

回答1:

From your description it seems that in your Excel the decimal delimiter is comma from your current locale settings. So this comma in {"0,5", "1", "1,5", "2", "2,5"} is in conflict with the comma used as list delimiter in list constraint formula. This is because this list constraint formula will be <formula1>"0,5,1,1,5,2,2,5"</formula1>.

When used {"0.5", "1", "1.5", "2", "2.5"}, the list constraint formula will be <formula1>"0.5,1,1.5,2,2.5"</formula1>. But now the dot in this formula is in conflict with your locale settings having comma as decimal delimiter and dot as delimiter in date literals.

This is a well known Excel problem. Current Excel versions are solving this by using a different kind of storing the list constraint: <x12ac:list>"0,5",1,"1,5",2,"2,5"</x12ac:list> instead of: <formula1>"0,5,1,1,5,2,2,5"</formula1>. But apache poi does not support this.

As a workaround I suggest using a hidden sheet to store the list items.

Example:

import java.io.*;

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;

import org.apache.poi.ss.util.*;

class CreateExcelDataValidationList {

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

   Workbook workbook = new XSSFWorkbook();  

   //create sheet for storing the list items:
   Sheet sheet = workbook.createSheet("ListSheet");
   sheet.createRow(0).createCell(0).setCellValue("SourceList");
   int r = 1;
   for (double d = 0.5; d < 3; d+=0.5) {
    sheet.createRow(r++).createCell(0).setCellValue(d);
   }
   //unselect that sheet because we will hide it later
   sheet.setSelected(false);
   //create a named range for the list contraint
   Name namedCell = workbook.createName();
   namedCell.setNameName("SourceList");
   String reference = "ListSheet!$A$2:$A$5";
   namedCell.setRefersToFormula(reference);

   //create the visible sheet
   sheet = workbook.createSheet("Sheet1");

   sheet.createRow(0).createCell(0).setCellValue("Take the ListItems from B1:");
   sheet.setActiveCell(new CellAddress("B1"));

   sheet.autoSizeColumn(0);

   //create the data validation
   DataValidationHelper dvHelper = sheet.getDataValidationHelper();
   DataValidationConstraint dvConstraint = dvHelper.createFormulaListConstraint("SourceList");
   CellRangeAddressList addressList = new CellRangeAddressList(0, 0, 1, 1);            
   DataValidation validation = dvHelper.createValidation(dvConstraint, addressList);

   sheet.addValidationData(validation);

   //hide the ListSheet
   workbook.setSheetHidden(0, true);
   //set Sheet1 active
   workbook.setActiveSheet(1);

   workbook.write(new FileOutputStream("CreateExcelDataValidationList.xlsx"));
   workbook.close();

 }
}