Apache POI - How to restrict the user to clear the data validations in excel sheet

Question

I have set up a Data validation on my sheet using Apache POI. The validation is like it allows only the decimal numbers. It was working fine without any issues. But when user cl

Answer 1

You should consider locking the sheet against changes and let only the cells unlocked which shall be editable. Example:

import java.io.*;

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

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

class LockDataValidation {

 public static void main(String[] args) {
  try {

   Workbook workbook = new XSSFWorkbook();

   Sheet sheet = workbook.createSheet("Sheet1");

   sheet.createRow(0).createCell(1).setCellValue("Only numbers 10 to 100");

   //DataValidation for cell B2:
   DataValidationHelper dvHelper = sheet.getDataValidationHelper();
   DataValidationConstraint dvConstraint = dvHelper.createNumericConstraint(
    DataValidationConstraint.ValidationType.INTEGER,
    DataValidationConstraint.OperatorType.BETWEEN,
    "10", "100");
   CellRangeAddressList addressList = new CellRangeAddressList(1, 1, 1, 1);            
   DataValidation validation = dvHelper.createValidation(dvConstraint, addressList);
   if(validation instanceof XSSFDataValidation) {
    validation.setSuppressDropDownArrow(false);
    validation.setShowErrorBox(true);
   }
   else {
    validation.setSuppressDropDownArrow(true);
   }
   sheet.addValidationData(validation);

   //create cell B2:
   Cell cell = sheet.createRow(1).createCell(1);

   //set cell B2 unlocked:
   CellStyle cellstyle = workbook.createCellStyle();
   cellstyle.setLocked(false);
   cell.setCellStyle(cellstyle);

   //lock the sheet:
   ((XSSFSheet)sheet).enableLocking();

   FileOutputStream fileOut = new FileOutputStream("Datavalidation.xlsx");
   workbook.write(fileOut);
   fileOut.close();

  } catch (FileNotFoundException fnfex) {
  } catch (IOException ioex) {
  }
 }
}

With this only B2 is editable and the data validation is protected against removing. Without locking the data validation will simply deleted if someone pastes a copied cell without validation into the cell with validation.

But even now one can copy/paste wrong values into B2 since data validation is designed to show messages and prevent invalid entries only when users type data directly in a cell. When data is copied or filled, the messages do not appear. See https://support.office.com/en-us/article/Apply-data-validation-to-cells-c743a24a-bc48-41f1-bd92-95b6aeeb73c9.

There are VBA macro solutions in the wild which are trying to close even this gap. See Data validation fails when copy pasting data in excel made through apache poi.