How to create a dependent drop down list using [Apache POI]

Question

Here I am creating one excel template using [Apache POI] in that user can fill data. In that two drop down list are there. Want to create a drop down list that depends on previous cell's drop down. For example: If I select veg category in cell 3, and "rice, curd, milk" items will appear in the dependent drop down list in cell 4. Codes are below.

Here collecting data

   List<InternetItemResponse> internetItems = internetItemService.getAllByHotelId(hotelId);
    if (CollectionUtils.isNotEmpty(internetItems)) {
    String[] itemsName = new String[internetItems.size()];
    String[] itemsCategory = new String[internetItems.size()];
    String itemName;
    String itemCategory;
    Map<String, Set<String>> categoryVsItemName = new HashMap<>();
    Set<String> itemList;
    for (int i = 0; i < internetItems.size(); i++) {
        InternetItemResponse itemResponse = internetItems.get(i);
        if (itemResponse != null) {
            itemCategory = itemResponse.getCategory();
            if (!StringUtils.isEmpty(itemCategory)) {
                itemsCategory[i] = itemCategory;
                itemName = itemResponse.getTitle();
                itemsName[i] = itemName;
                if (CollectionUtils.isEmpty(categoryVsItemName.get(itemCategory))) {
                    itemList = new HashSet<>();
                    itemList.add(itemName);
                    categoryVsItemName.put(itemCategory, itemList);
                } else {
                    categoryVsItemName.get(itemCategory).add(itemName);
                }
            }
        }
    }
}

Assigning the data in drop down

// Setting drop down values
    for (int i = 0; i < headerColumns.length; i++) {
        if (i == 3) {
            XSSFDataValidationHelper mealdvHelper = new XSSFDataValidationHelper((XSSFSheet) sheet);
            XSSFDataValidationConstraint mealdvConstraint = (XSSFDataValidationConstraint) mealdvHelper
                    .createExplicitListConstraint(itemsCategory);
            // CellRangeAddressList(int firstRow, int lastRow, int firstCol, int lastCol)
            CellRangeAddressList addressListmeal = new CellRangeAddressList(1, 99, i, i);
            XSSFDataValidation categoryDataValidation = (XSSFDataValidation) mealdvHelper
                    .createValidation(mealdvConstraint, addressListmeal);
            categoryDataValidation.setShowErrorBox(true);
            categoryDataValidation.setSuppressDropDownArrow(true);
            categoryDataValidation.setShowPromptBox(true);
            sheet.addValidationData(categoryDataValidation);
        } else if (i == 4) {
            XSSFDataValidationHelper rmCategorydvHelper = new XSSFDataValidationHelper((XSSFSheet) sheet);
            XSSFDataValidationConstraint rmCategorydvConstraint = (XSSFDataValidationConstraint) rmCategorydvHelper
                    .createExplicitListConstraint(itemsName);
            CellRangeAddressList addressListrmCategory = new CellRangeAddressList(1, 99, i, i);
            XSSFDataValidation itemNameValidation = (XSSFDataValidation) rmCategorydvHelper
                    .createValidation(rmCategorydvConstraint, addressListrmCategory);
            itemNameValidation.setShowErrorBox(true);
            itemNameValidation.setSuppressDropDownArrow(true);
            itemNameValidation.setShowPromptBox(true);
            sheet.addValidationData(itemNameValidation);
        }
    }

Answer 1

Creating dependent dropdown lists is nothing what apache poi could do. The apache poi library is made for creating Excel files. The dependency of dropdown lists must be managed in Excels GUI where the generated file is running in. Apache poi only can create the Excel file so that this is possible then.

One approach is using named ranges for the data validation lists who's names are then got using INDIRECT. So the main list contains the names of the named ranges of the dependent lists. And the dependent list uses =INDIRECT([cell of main list]) then to get the dependent list who's name is selected from main list.

Example of how this can be created using apache poi:

import java.io.FileOutputStream;

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

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

import java.util.Map;
import java.util.HashMap;

class CreateExcelDependentDataValidationListsUsingNamedRanges {

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

   //some data
   Map<String, String[]> categoryItems = new HashMap<String, String[]>();
   categoryItems.put("Countries", new String[]{"France", "Germany", "Italy"});
   categoryItems.put("Capitals", new String[]{"Paris", "Berlin", "Rome"});
   categoryItems.put("Fruits", new String[]{"Apple", "Peach", "Banana", "Orange"});

   Workbook workbook = new XSSFWorkbook();

   //hidden sheet for list values
   Sheet sheet = workbook.createSheet("ListSheet");

   Row row;  
   Name namedRange;
   String colLetter;
   String reference;

   int c = 0;
   //put the data in
   for (String key : categoryItems.keySet()) {
    int r = 0;
    row = sheet.getRow(r); if (row == null) row = sheet.createRow(r); r++;
    row.createCell(c).setCellValue(key);
    String[] items = categoryItems.get(key);
    for (String item : items) {
     row = sheet.getRow(r); if (row == null) row = sheet.createRow(r); r++;
     row.createCell(c).setCellValue(item);
    }
    //create names for the item list constraints, each named from the current key
    colLetter = CellReference.convertNumToColString(c);
    namedRange = workbook.createName();
    namedRange.setNameName(key);
    reference = "ListSheet!$" + colLetter + "$2:$" + colLetter + "$" + r;
    namedRange.setRefersToFormula(reference);
    c++;
   }

   //create name for Categories list constraint
   colLetter = CellReference.convertNumToColString((c-1));
   namedRange = workbook.createName();
   namedRange.setNameName("Categories");
   reference = "ListSheet!$A$1:$" + colLetter + "$1";
   namedRange.setRefersToFormula(reference);

   //unselect that sheet because we will hide it later
   sheet.setSelected(false);


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

   sheet.createRow(0).createCell(0).setCellValue("Select Category");
   sheet.getRow(0).createCell(1).setCellValue("Select item from that category");

   sheet.setActiveCell(new CellAddress("A2"));

   sheet.autoSizeColumn(0);
   sheet.autoSizeColumn(1);

   //data validations
   DataValidationHelper dvHelper = sheet.getDataValidationHelper();
   //data validation for categories in A2:
   DataValidationConstraint dvConstraint = dvHelper.createFormulaListConstraint("Categories");
   CellRangeAddressList addressList = new CellRangeAddressList(1, 1, 0, 0);            
   DataValidation validation = dvHelper.createValidation(dvConstraint, addressList);
   sheet.addValidationData(validation);

   //data validation for items of the selected category in B2:
   dvConstraint = dvHelper.createFormulaListConstraint("INDIRECT($A$2)");
   addressList = new CellRangeAddressList(1, 1, 1, 1);            
   validation = dvHelper.createValidation(dvConstraint, addressList);
   sheet.addValidationData(validation);

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

   FileOutputStream out = new FileOutputStream("CreateExcelDependentDataValidationListsUsingNamedRanges.xlsx");
   workbook.write(out);
   workbook.close();
   out.close();

 }
}