Java tutorial
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See the License for the specific language governing permissions and limitations under the License. ==================================================================== */ package org.excel; import java.io.*; import org.apache.poi.xssf.usermodel.*; import org.apache.poi.hssf.usermodel.*; import org.apache.poi.ss.usermodel.*; import org.apache.poi.ss.util.CellRangeAddressList; /** * Demonstrates one technique that may be used to create linked or dependent * drop down lists. This refers to a situation in which the selection made * in one drop down list affects the options that are displayed in the second * or subsequent drop down list(s). In this example, the value the user selects * from the down list in cell A1 will affect the values displayed in the linked * drop down list in cell B1. For the sake of simplicity, the data for the drop * down lists is included on the same worksheet but this does not have to be the * case; the data could appear on a separate sheet. If this were done, then the * names for the regions would have to be different, they would have to include * the name of the sheet. * * There are two keys to this technique. The first is the use of named area or * regions of cells to hold the data for the drop down lists and the second is * making use of the INDIRECT() function to convert a name into the addresses * of the cells it refers to. * * Note that whilst this class builds just two linked drop down lists, there is * nothing to prevent more being created. Quite simply, use the value selected * by the user in one drop down list to determine what is shown in another and the * value selected in that drop down list to determine what is shown in a third, * and so on. Also, note that the data for the drop down lists is contained on * contained on the same sheet as the validations themselves. This is done simply * for simplicity and there is nothing to prevent a separate sheet being created * and used to hold the data. If this is done then problems may be encountered * if the sheet is opened with OpenOffice Calc. To prevent these problems, it is * better to include the name of the sheet when calling the setRefersToFormula() * method. * * @author Mark Beardsley [msb at apache.org] * @version 1.00 30th March 2012 */ public class LinkedDropDownLists { LinkedDropDownLists(String workbookName) { File file = null; FileOutputStream fos = null; Workbook workbook = null; Sheet sheet = null; DataValidationHelper dvHelper = null; DataValidationConstraint dvConstraint = null; DataValidation validation = null; CellRangeAddressList addressList = null; try { // Using the ss.usermodel allows this class to support both binary // and xml based workbooks. The choice of which one to create is // made by checking the file extension. if (workbookName.endsWith(".xlsx")) { workbook = new XSSFWorkbook(); } else { workbook = new HSSFWorkbook(); } // Build the sheet that will hold the data for the validations. This // must be done first as it will create names that are referenced // later. sheet = workbook.createSheet("Linked Validations"); LinkedDropDownLists.buildDataSheet(sheet); // Build the first data validation to occupy cell A1. Note // that it retrieves it's data from the named area or region called // CHOICES. Further information about this can be found in the // static buildDataSheet() method below. addressList = new CellRangeAddressList(0, 0, 0, 0); dvHelper = sheet.getDataValidationHelper(); dvConstraint = dvHelper.createFormulaListConstraint("CHOICES"); validation = dvHelper.createValidation(dvConstraint, addressList); sheet.addValidationData(validation); // Now, build the linked or dependent drop down list that will // occupy cell B1. The key to the whole process is the use of the // INDIRECT() function. In the buildDataSheet(0 method, a series of // named regions are created and the names of three of them mirror // the options available to the user in the first drop down list // (in cell A1). Using the INDIRECT() function makes it possible // to convert the selection the user makes in that first drop down // into the addresses of a named region of cells and then to use // those cells to populate the second drop down list. addressList = new CellRangeAddressList(0, 0, 1, 1); dvConstraint = dvHelper.createFormulaListConstraint("INDIRECT(UPPER($A$1))"); validation = dvHelper.createValidation(dvConstraint, addressList); sheet.addValidationData(validation); file = new File(workbookName); fos = new FileOutputStream(file); workbook.write(fos); } catch (IOException ioEx) { System.out.println("Caught a: " + ioEx.getClass().getName()); System.out.println("Message: " + ioEx.getMessage()); System.out.println("Stacktrace follws:....."); ioEx.printStackTrace(System.out); } finally { try { if (fos != null) { fos.close(); fos = null; } } catch (IOException ioEx) { System.out.println("Caught a: " + ioEx.getClass().getName()); System.out.println("Message: " + ioEx.getMessage()); System.out.println("Stacktrace follws:....."); ioEx.printStackTrace(System.out); } } } /** * Called to populate the named areas/regions. The contents of the cells on * row one will be used to populate the first drop down list. The contents of * the cells on rows two, three and four will be used to populate the second * drop down list, just which row will be determined by the choice the user * makes in the first drop down list. * * In all cases, the approach is to create a row, create and populate cells * with data and then specify a name that identifies those cells. With the * exception of the first range, the names that are chosen for each range * of cells are quite important. In short, each of the options the user * could select in the first drop down list is used as the name for another * range of cells. Thus, in this example, the user can select either * 'Animal', 'Vegetable' or 'Mineral' in the first drop down and so the * sheet contains ranges named 'ANIMAL', 'VEGETABLE' and 'MINERAL'. * * @param dataSheet An instance of a class that implements the Sheet Sheet * interface (HSSFSheet or XSSFSheet). */ private static final void buildDataSheet(Sheet dataSheet) { Row row = null; Cell cell = null; Name name = null; // The first row will hold the data for the first validation. row = dataSheet.createRow(10); cell = row.createCell(0); cell.setCellValue("Animal"); cell = row.createCell(1); cell.setCellValue("Vegetable"); cell = row.createCell(2); cell.setCellValue("Mineral"); name = dataSheet.getWorkbook().createName(); name.setRefersToFormula("$A$11:$C$11"); name.setNameName("CHOICES"); // The next three rows will hold the data that will be used to // populate the second, or linked, drop down list. row = dataSheet.createRow(11); cell = row.createCell(0); cell.setCellValue("Lion"); cell = row.createCell(1); cell.setCellValue("Tiger"); cell = row.createCell(2); cell.setCellValue("Leopard"); cell = row.createCell(3); cell.setCellValue("Elephant"); cell = row.createCell(4); cell.setCellValue("Eagle"); cell = row.createCell(5); cell.setCellValue("Horse"); cell = row.createCell(6); cell.setCellValue("Zebra"); name = dataSheet.getWorkbook().createName(); name.setRefersToFormula("$A$12:$G$12"); name.setNameName("ANIMAL"); row = dataSheet.createRow(12); cell = row.createCell(0); cell.setCellValue("Cabbage"); cell = row.createCell(1); cell.setCellValue("Cauliflower"); cell = row.createCell(2); cell.setCellValue("Potato"); cell = row.createCell(3); cell.setCellValue("Onion"); cell = row.createCell(4); cell.setCellValue("Beetroot"); cell = row.createCell(5); cell.setCellValue("Asparagus"); cell = row.createCell(6); cell.setCellValue("Spinach"); cell = row.createCell(7); cell.setCellValue("Chard"); name = dataSheet.getWorkbook().createName(); name.setRefersToFormula("$A$13:$H$13"); name.setNameName("VEGETABLE"); row = dataSheet.createRow(13); cell = row.createCell(0); cell.setCellValue("Bauxite"); cell = row.createCell(1); cell.setCellValue("Quartz"); cell = row.createCell(2); cell.setCellValue("Feldspar"); cell = row.createCell(3); cell.setCellValue("Shist"); cell = row.createCell(4); cell.setCellValue("Shale"); cell = row.createCell(5); cell.setCellValue("Mica"); name = dataSheet.getWorkbook().createName(); name.setRefersToFormula("$A$14:$F$14"); name.setNameName("MINERAL"); } }