Develop Reference

After using Apache POI to edit and existing Excel file, the formulas that use does cells disappear

I am using Apache POI to edit an existing file. This file contains multiple formulas that use the numbers that will be inputted through Apache. And this is where I run into problems, when a number is inputted and that cell is being used in a formula, the file gets corrupted and the formula disappears.
Here the formulas for the 0 are C7+D7, C8+D8, etc.
Here the formulas for the 0 became normal 0, the formulas got lost.
Here is the code I used to write to the excel file:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.EncryptedDocumentException;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
public class write {
public static void main(String[] args) {
String excelFilePath = "C:\\Users\\jose_\\IdeaProjects\\writeExcel\\src\\JavaBooks.xlsx";
try {
FileInputStream inputStream = new FileInputStream(new File(excelFilePath));
Workbook workbook = WorkbookFactory.create(inputStream);
Sheet sheet = workbook.getSheetAt(0);
/*Cell cell2Update = sheet.getRow(1).getCell(3); // This updates a specific cell: row 0 cell 3
cell2Update.setCellValue(49);*/
Object[][] bookData = {
{2, 17},
{3, 27},
{4, 33},
{5, 44},
};
// int rowCount = sheet.getLastRowNum(); // Gets the last entry
int rowCount = 5;
for (Object[] aBook : bookData) {
Row row = sheet.createRow(++rowCount);
int columnCount = 1;
int lote = 1;
Cell cell = row.createCell(columnCount);
//cell.setCellValue(rowCount); // This sets the index for each entry
cell.setCellValue(lote);
for (Object field : aBook) {
cell = row.createCell(++columnCount);
if (field instanceof String) {
cell.setCellValue((String) field);
} else if (field instanceof Integer) {
cell.setCellValue((Integer) field);
}
}
}
inputStream.close();
FileOutputStream outputStream = new FileOutputStream("C:\\Users\\jose_\\IdeaProjects\\writeExcel\\src\\JavaBooks.xlsx");
workbook.write(outputStream);
workbook.close();
outputStream.close();
} catch (IOException | EncryptedDocumentException ex) {
ex.printStackTrace();
}
}
}
Is there a way to work around this or do I need to set all the formulas again through Apache POI?

You get the error because using code line Row row = sheet.createRow(++rowCount); you always create new empty rows and so you remove all cells in those rows. So you are also removing the cells containing the formulas. Doing so you are damaging the calculation chain. That's what the Excel GUI tells you with the messages.
You should not do this. Instead you always should try to get the rows first using Sheet.getRow. Only if that returns null then you need to create the row.
...
//Row row = sheet.createRow(++rowCount);
Row row = sheet.getRow(rowCount); if (row == null) row = sheet.createRow(rowCount); rowCount++;
...
Additional please read Recalculation of Formulas. So after changing cells referenced in formulas, do always either workbook.getCreationHelper().createFormulaEvaluator().evaluateAll(); or delegate re-calculation to Excel using workbook.setForceFormulaRecalculation(true);.

Read Write Excel File in java

package demo;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class Readwrite {
public static void main(String[] args) throws Exception
{
//Get the excel file and create an input stream for excel
FileInputStream fis = new FileInputStream("D:\\Testing_Team\\Age_Validation.xlsx");
//load the input stream to a workbook object
//Use XSSF for (.xlsx) excel file and HSSF for (.xls) excel file
XSSFWorkbook wb = new XSSFWorkbook(fis);
//get the sheet from the workbook by index
XSSFSheet sheet = wb.getSheet("Age");
//Count the total number of rows present in the sheet
int rowcount = sheet.getLastRowNum();
System.out.println(" Total number of rows present in the sheet : "+rowcount);
//get column count present in the sheet
int colcount = sheet.getRow(1).getLastCellNum();
System.out.println(" Total number of columns present in the sheet : "+colcount);
//get the data from sheet by iterating through cells
//by using for loop
for(int i = 1; i<=rowcount; i++)
{
XSSFCell cell = sheet.getRow(i).getCell(1);
String celltext="";
//Get celltype values
if(cell.getCellType()==Cell.CELL_TYPE_STRING)
{
celltext=cell.getStringCellValue();
}
else if(cell.getCellType()==Cell.CELL_TYPE_NUMERIC)
{
celltext=String.valueOf(cell.getNumericCellValue());
}
else if(cell.getCellType()==Cell.CELL_TYPE_BLANK)
{
celltext="";
}
//Check the age and set the Cell value into excel
if(Double.parseDouble(celltext)>=18)
{
sheet.getRow(i).getCell(2).setCellValue("Major");
}
else
{
sheet.getRow(i).getCell(2).setCellValue("Minor");
}
}//End of for loop
//close the file input stream
fis.close();
//Open an excel to write the data into workbook
FileOutputStream fos = new FileOutputStream("D:\\Testing_Team\\Age_Validation.xlsx");
//Write into workbook
wb.write(fos);
//close fileoutstream
fos.close();
}
}
*I am getting error like [ Exception in thread "main" java.lang.NullPointerException
at demo.Readwrite.main(Readwrite.java:31) ] .
Can Someone please guide me for the same.
I have watched this video for reference https://www.youtube.com/watch?v=orYZB_RUgNc
I have added two poi dependency also poi-ooxml and poi.
Waiting for your valuable response.*

As you comment shows that, you should send index number rather than column name,
I think 'Age' is a column name of you sheet.
//get the sheet from the workbook by index
XSSFSheet sheet = wb.getSheetAt(0);
please replace above line in you code and run it.

Excel import from csv file to convert

Im having difficulty with using Apache POI API. Im trying to import an excel them only select certain rows and cells to extract from the import. Im currently able to import, but i cant extract certain cell. Here is code:
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import java.io.File;
import java.io.IOException;
public class ExcelReader {
public static final String path = "C:/Users/xxxx/Documents/import testing.xlsx";
public static void main(String[] args) throws IOException, InvalidFormatException {
// Create a workbook with data from excel file
Workbook workbook = WorkbookFactory.create(new File(path));
// Save sheets from workbook
Sheet sheet = workbook.getSheetAt(0);
// Make sure the data is saved in string format using a data formatter
DataFormatter dataFormatter = new DataFormatter();
// Iterate through cells and columns, printing their content
System.out.println("\n\nThe content of the excel file: " + path + "\n");
String cellContent;
for (Row row: sheet) {
for(Cell cell: row) {
cellContent = dataFormatter.formatCellValue(cell);
if(cellContent == null || cellContent.trim().isEmpty()){
// Give the empty cells the content "empty", to make it easy to filter out later on
cellContent = "empty";
}
System.out.print(cellContent + "\t");
}
CellReference cellReference = new CellReference("A11");
XSSFRow rowT = sheet.getRow(cellReference.getRow());
if (rowT != null) {
XSSFCell cell = rowT.getCell(cellReference.getCol());
}
System.out.println();
}
// Close the connection to the workbook
workbook.close();
}
}

Changing Workbook to XSSFWorkbook and Sheet to XSSFSheet seems to fix the compilation issue.
XSSFWorkbook workbook = new XSSFWorkbook(new File(path));
and
XSSFSheet sheet = workbook.getSheetAt(0);

try with this for get "A11" cell
XSSFCell cell = sheet.getRow(10).getCell(0); // 10 = id of the 11th row, 0 = id of the 1st (A) column
or
XSSFCell cell = sheet.getRow(10).getCell(CellReference.convertColStringToIndex("A"));
create cell reference for B12
CellReference cr = new CellReference("B12");
row = mySheet.getRow(cr.getRow());
cell = row.getCell(cr.getCol());

Updating Excel sheet values based on a csv sheet with Apache POI

I am still new to java. I am having a bit problems with the java syntax.
My Program should do the following procedure:
1) It takes a csv file as an input.
2) It takes an excel file as an input.
3) It should iterate over the first columns of the two files where the dates are written.
4) Update the excel file by adding the information from the csv sheet and save its changes.
I have a https://onedrive.live.com/?cid=24b4fceb4f4e4098&id=24B4FCEB4F4E4098%213018&authkey=%21AKKzaZsJ5pkd5NE
where I have the two input examples and how the result excel sheet should look like.
Two Input files:
export-csv-input.csv
export-excel-input.xlsx
The updated excel file should look like:
export-excel-output.xlsx
My Java Code yet:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.DataFormatter;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class CsvToExcelConverter {
public static final String SAMPLE_XLSX_FILE_PATH =
"C:/Users/blawand/Desktop/CSV_to_Excel/export-excel-test.xlsx";
public static final String SAMPLE_CSV_FILE_PATH =
"C:/Users/blawand/Desktop/CSV_to_Excel/export-csv-test.csv";
public static List<String> dates_csv = new ArrayList<>();
public static List<String> dates_excel = new ArrayList<>();
public static void main(String[] args) throws IOException,
InvalidFormatException {
try (Reader reader =
Files.newBufferedReader(Paths.get(SAMPLE_CSV_FILE_PATH));
CSVParser csvParser = new CSVParser(reader, CSVFormat.DEFAULT);)
{
for (CSVRecord csvRecord : csvParser) {
// Accessing Values by Column Index
String name = csvRecord.get(0);
dates_csv.add(name);
}
dates_csv.remove(0);
}
FileInputStream fsIP = new FileInputStream(new
File(SAMPLE_XLSX_FILE_PATH));
/*
* ==================================================================
Iterating over all the
* rows and columns in a Sheet (Multiple ways)
* ==================================================================
*/
// Getting the Sheet at index zero
XSSFWorkbook workbook = new XSSFWorkbook(fsIP);
XSSFSheet sheet = workbook.getSheetAt(0);
// Get the Cell at index 2 from the above row
// Cell cell1 = sheet.getRow(1).getCell(0);
// for (int i = 0; i < dates_excel.size(); i++) {
// XSSFRow rowtest = sheet.createRow((short) i + 1);
// rowtest.createCell(0).setCellValue(dates_csv.get(i));
//
// }
// cell1.setCellValue(dates_csv.get(0));
// Create a DataFormatter to format and get each cell's value as
String
DataFormatter dataFormatter = new DataFormatter();
for (int rowIndex = 1; rowIndex <= sheet.getLastRowNum(); rowIndex++)
{
Row row = sheet.getRow(rowIndex);
if (row != null) {
Cell cell = row.getCell(0); // getColumn(0)
if (cell != null) {
// Found column and there is value in the cell.
// String cellValueMaybeNull = cell.getStringCellValue();
String cellValueMaybeNull =
dataFormatter.formatCellValue(cell);
// String to number set
dates_excel.add(cellValueMaybeNull);
}
}
}
System.out.println(dates_csv);
System.out.println(dates_csv.size());
System.out.println(dates_excel);
System.out.println(dates_excel.size());
while (dates_excel == dates_excel) {
System.out.println("Yes");
break;
}
fsIP.close();
FileOutputStream output_file = new FileOutputStream(new
File(SAMPLE_XLSX_FILE_PATH));
workbook.write(output_file);
output_file.close();
}
}
I read already the two files but i am having problems with updating the excel file and adding the project names to the correct dates. And if the same date has been written two or more times in the csv sheet.
Which information would you like also to know?
I would be thankful for every help or advice!

I have an example for you, mostly explained by code comments. Nevertheless, the code basically does the following:
Takes file paths of the xlsx and csv file in the constructor.
When updating, it first reads the content of the csv file into a Map with a LocalDate as key and a List<String> as values.
Then it goes through the rows of the workbook skipping the header row and comparing the dates in column one with the keys of the Map<LocalDate, List<String>>. If the map contains that key, it starts checking the cells in that row for present values and keeps them in a list in order to not write them later.
Then it starts writing the values into the cells of the row with the key date.
I hope this helps.
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class CsvXlsxUpdater {
private static final DateTimeFormatter DATE_TIME_FORMATTER_CSV = DateTimeFormatter.ofPattern("dd.MM.yyyy");
private Path csvFilePath;
private Path xlsxFilePath;
private XSSFWorkbook workbook;
private XSSFSheet sheet;
private Map<LocalDate, List<String>> csvContent = new TreeMap<LocalDate, List<String>>();
private ZoneId zoneId = ZoneId.systemDefault();
public CsvXlsxUpdater(String pathToCsvFile, String pathToXlsxFile) {
csvFilePath = Paths.get(pathToCsvFile);
xlsxFilePath = Paths.get(pathToXlsxFile);
}
/**
* Reads the content of the csv file into the corresponding class variable,
* which is a {#link TreeMap} that has a {#link LocalDate} as key and a
* {#link List<String>} as values.
*/
private void readCsvContent() {
List<String> csvLines;
try {
csvLines = Files.readAllLines(csvFilePath);
for (int i = 1; i < csvLines.size(); i++) {
String line = csvLines.get(i);
String[] splitValues = line.split(",");
if (splitValues.length > 1) {
List<String> lineValues = Arrays.asList(splitValues);
List<String> projects = getProjectValuesFrom(lineValues);
LocalDate localDate = LocalDate.parse(lineValues.get(0), DATE_TIME_FORMATTER_CSV);
if (csvContent.containsKey(localDate)) {
projects.forEach((String project) -> {
List<String> csvProjects = csvContent.get(localDate);
if (!csvProjects.contains(project)) {
csvProjects.add(project);
}
});
} else {
csvContent.put(localDate, projects);
}
} else {
LocalDate localDate = LocalDate.parse(splitValues[0], DATE_TIME_FORMATTER_CSV);
csvContent.put(localDate, new ArrayList<String>());
}
}
} catch (IOException e) {
System.err.println("CANNOT FIND OR READ CSV FILE: " + e.getMessage());
e.printStackTrace();
} catch (UnsupportedOperationException e) {
System.err.println("UNSUPPORTED OPERATION: " + e.getMessage());
e.printStackTrace();
}
}
/**
* Gets the corresponding {#link LocalDate} from a given (and deprecated)
* {#link Date}
*
* #param date the deprecated {#link Date} object
* #return the corresponding {#link LocalDate}
*/
private LocalDate parseLocalDateFrom(Date date) {
Instant instantDate = date.toInstant();
return instantDate.atZone(zoneId).toLocalDate();
}
/**
* Takes a list of read values from the csv file and returns a list containing
* all the values of the given list <strong>except from the first
* element</strong>, which is a {#link String} representation of a date and
* should be treated differently in this context.
*
* #param values the original list of {#link String}s
* #return another list without the first element of the given list
*/
private List<String> getProjectValuesFrom(List<String> values) {
List<String> projectValues = new ArrayList<String>();
for (int i = 1; i < values.size(); i++) {
String value = values.get(i);
if (!value.equals("")) {
projectValues.add(value);
}
}
return projectValues;
}
/**
* Updates the workbook with the values read from the csv file
*/
public void updateWorkbook() {
readCsvContent();
try {
FileInputStream fis = new FileInputStream(xlsxFilePath.toAbsolutePath().toString());
workbook = new XSSFWorkbook(fis);
sheet = workbook.getSheetAt(0);
// iterate over the rows
Iterator<Row> rowIterator = sheet.rowIterator();
while (rowIterator.hasNext()) {
XSSFRow row = (XSSFRow) rowIterator.next();
if (row.getRowNum() == 0) {
// skip this or set updated headers
} else {
// check if the csvContent contains the value of cell(0)
LocalDate dateKey = parseLocalDateFrom(row.getCell(0).getDateCellValue());
if (csvContent.containsKey(dateKey)) {
// if yes, get list-value of the key
List<String> values = csvContent.get(dateKey);
// check if there are values
if (values != null) {
if (values.size() > 0) {
// if there are, then go checking the cell values
List<String> projectsInXlsx = new ArrayList<String>();
Iterator<Cell> cellIterator = row.cellIterator();
int lastColumnIndex = 1;
// go through all cells with a value except from the first one
while (cellIterator.hasNext()) {
Cell cell = cellIterator.next();
// skip the first column as it contains the date
if (cell.getColumnIndex() != 0) {
lastColumnIndex = cell.getColumnIndex();
System.out.println("Accessing cell in column " + lastColumnIndex);
// if there is a cell with a value
if (cell.getStringCellValue() != null) {
if (!cell.getStringCellValue().equals("")) {
// check if the value in the cell is also in the csv values
if (values.contains(cell.getStringCellValue())) {
projectsInXlsx.add(cell.getStringCellValue());
lastColumnIndex++;
}
}
}
}
}
// now go through the values of the csv file
int offset = 0; // cell column offset for more than one entry per date
for (String value : values) {
if (!projectsInXlsx.contains(value)) {
// create a cell after the last one with a value
row.createCell(lastColumnIndex + offset).setCellValue(value);
offset++;
}
}
}
}
}
}
}
fis.close();
FileOutputStream fileOutputStream = new FileOutputStream(xlsxFilePath.toAbsolutePath().toString());
workbook.write(fileOutputStream);
fileOutputStream.flush();
fileOutputStream.close();
workbook.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In a main method, you would just have to call the constructor, pass the file paths as Strings and then call the updateWorkbook() method, because it internally reads the csv first.
Example:
public class CsvXlsxMain {
private static final String CSV_FILE_PATH = "S:\\ome\\example\\path\\to\\csv-input.csv";
private static final String XLSX_FILE_PATH = "S:\\ome\\example\\path\\to\\excel-input.xlsx";
public static void main(String[] args) {
CsvXlsxUpdater cxu = new CsvXlsxUpdater(CSV_FILE_PATH, XLSX_FILE_PATH);
cxu.updateWorkbook();
}
}
Please keep in mind that this CODE IS NOT FULLY TESTED, there may be problems with alternating resources in future
If you need, go testing it with various xlsx and csv inputs that fit your requirements.
I haven't used any library to parse the csv file!
I hope this helps you a little…

reading xlsx and import it

I am trying to create a class to read a XLSX file when I upload it to a website.
I have the code to upload the file to the server. The file can be uploaded but it can't capture the data from the excel.
May I know how do I solve or modify this code such that the data is being able to be seen on the web?
I know there's some other duplicate questions out there but after trying, those answers can't seem to work for me.
If I remove the line public static void... , then I will get this error: Package should contain a content type part [M1.13]
public HashMap getConstructJXLList_xlsx(UploadedFile File, int Sheetindex) {
String _LOC = "[PageCodeBase: getConstructJXLList_xlsx]";
HashMap _m = new HashMap();
return _m;
}
//InputStream _is = null;
public static void main(String[] args)
{
try {
FileInputStream input = new FileInputStream(new File("C:\\Users\\admin\\Desktop\\Load_AcctCntr_Template.xlsx"));
org.apache.poi.ss.usermodel.Workbook wb = WorkbookFactory.create(input);
org.apache.poi.ss.usermodel.Sheet s = wb.getSheetAt(0);
Iterator<Row> rows = s.rowIterator();
while (rows.hasNext())
{
Row row = rows.next();
Iterator cells = row.cellIterator();
while (cells.hasNext())
{
XSSFCell cell = (XSSFCell) cells.next();
if (cell.getCellType() == XSSFCell.CELL_TYPE_STRING)
{
System.out.print(cell.getStringCellValue() + "t");
}
else if(cell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC)
{
System.out.print(cell.getNumericCellValue() + "t");
}
else if(cell.CELL_TYPE_BLANK==cell.getCellType())
System.out.print( "BLANK " );
else
System.out.print("Unknown cell type");
}
input.close();
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
If I just run the main method from above, this is the output:
0000002b SystemOut O [RedirectLogin: requiredRights]1.0en1102.xhtml
0000002b SystemOut O [En1102: doEn1102_command_readfileAction]1.0
0000002b SystemOut O [En1102: onPageLoadBegin]1.0
it seems that the server did not even run through this code above..
I can just download the excel template on the website and it will be saved on my desktop.
The file will contain the title header and I am able to key in whatever data I want in the cells.

To read xlsx files, you should use:
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
XSSFWorkbook wb;
XSSFSheet sheet;
XSSFRow row;
XSSFCell cell;
FileInputStream input = new FileInputStream(new File("C:\\Users\\admin\\Desktop\\Load_AcctCntr_Template.xlsx"));
wb = new XSSFWorkbook(input );