I have a script that reads a row in an excel sheet, fills an array list with the contents of each cell in that row, and writes it to a text file. I want to be able to write it to a pdf file (using iText) so that I can include an image in the file as well. The problem is I keep getting an error stating that the document has been closed and "Elements cannot be added" to the document. Here is the relevant code:
public File processFile(File excelWorkbook) throws FileNotFoundException, IOException, DocumentException{
System.out.println("Processing file...");
FileInputStream fileInputStream = new FileInputStream(excelWorkbook);
HSSFWorkbook workbook = new HSSFWorkbook(fileInputStream);
HSSFSheet firstSheet = workbook.getSheetAt(0);
Iterator<Row> rowIterator = firstSheet.iterator();
System.out.println("Please choose output file name.");
String fName = this.chooseFileName();
try{
for(int cntr=1; cntr<=firstSheet.getPhysicalNumberOfRows(); cntr++){
ArrayList<String> values = new ArrayList<String>();
Row currentRow = firstSheet.getRow(cntr);
for(int cntr2 = 0; cntr2<currentRow.getLastCellNum(); cntr2++){
Cell currentCell = currentRow.getCell(cntr2, Row.RETURN_NULL_AND_BLANK);
if(currentCell==null){
//cell doesn't have anything in there
values.add("-not in excel file-");
continue;
}else{
switch(currentCell.getCellType()){
case Cell.CELL_TYPE_STRING:
values.add(currentCell.getStringCellValue());
break;
case Cell.CELL_TYPE_NUMERIC:
double num = currentCell.getNumericCellValue();
String numString = String.valueOf(num);
values.add(numString);
break;
}
}
}
//libF = writeArrayListToFile(values, fName);
writePDF(values, fName);//the method that writes to pdf
}
}catch (NullPointerException e){
System.out.println("Cell is null.");
//e.printStackTrace();
}
fileInputStream.close();
return libF;
}
Here is the writePDF(ArrayList al, String fName) method:
public void writePDF(ArrayList<String> al, String filepath) throws FileNotFoundException, DocumentException{
PdfWriter.getInstance(document, new FileOutputStream(filepath));
document.open();
document.add(new Paragraph("Library"));
for(String i: al){
document.add(new Phrase(i+"\n"));
}
document.close();
}
Why am I not able to write to this file continuously? If I write to a text file, I can close it and open it again easily, so I can get all the information from the excel spreadsheet into a text file. The same does not seem to apply to a pdf file. It is unable to open and close easily. Can someone tell me how I should modify my code? All I want is for the script to read the Row in the excel sheet, add the Cell contents to the array list, and add the array list immediately after that to the pdf document. It just needs to do this for every row. This works for a text file but not for a pdf.
you are writing every row into a pdf document
your writePDF function has a field:
document
which isn't initialized around file opening (instead i think it's initialized in construction time)
initialize the document the same time you open the output file
Related
I am trying to write an excel file using java. I'm looking for just simply a column with one username per row right now, and then will build upon this later once I understand what is going a bit better. I get a zip file instead of the expected excel file, and it contains docProps, _rels, xl, and [Content_Types].xml. I don't understand how to open this zip file as though it is an excel file. I have not had luck finding the answer as all the tutorials I see show it to be a straight forward excel file, not a zip file. Is it a configuration I'm missing or is it to do with linux?
Here's my code, and what I end up with:
private void createExcelSheet(Assignment assignment) throws FileNotFoundException {
String excelFilePath = Configuration.DIRECTORY_ROOT+"/tests/"+assignment.getAssn_number()+"/gradebook-"+assignment.getAssn_number();
int rowNum = 0;
int col = 0;
XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet spreadsheet = workbook.createSheet(assignment.getAssn_number()+" Grades ");
XSSFRow row = spreadsheet.createRow(rowNum);
Cell cell;
for (User user : userService.getUsers() ) {
row = spreadsheet.createRow(rowNum);
cell = row.createCell(rowNum);
cell.setCellValue(user.getStudent_id());
rowNum++;
}
try (FileOutputStream fos = new FileOutputStream(excelFilePath)) {
workbook.write(fos);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
I am working with a large excel file ( larger than 40 Mb , more than 100k rows and 50 columns ). I am successfully reading it using POI ( 3.10.1 version ) event stream and then doing some calculation and storing result into a List.
Now I have to append this List as a column in the same file. In this part I am facing issue.
I have tried to achieve this by using the below code
FileInputStream excelFile = new FileInputStream(new File(pathToFile));
Workbook workbook = new XSSFWorkbook(excelFile);
Sheet datatypeSheet = workbook.getSheetAt(0); // Get first sheet
Iterator<Row> iterator = datatypeSheet.iterator();
int i=0;
while (iterator.hasNext()) { // Loop over each row
Row currentRow = iterator.next();
Cell cell = currentRow.createCell(currentRow.getLastCellNum());
cell.setCellType(Cell.CELL_TYPE_STRING);
if(currentRow.getRowNum() == 0)
cell.setCellValue("OUTPUT-COLUMN"); // set column header for the new column
else {
cell.setCellValue(list.get(i)); // list contains the output to populate in new column
i++;
}
}
FileOutputStream fos = new FileOutputStream(new File(pathToOutput));
workbook.write(fos);
fos.close();
It is working fine with smaller files But the issue is that I am getting Out of memory for the larger files. Now I tried to modify this and use SXSSF in place of XSFF to get over the memory issue (See below code). But while testing even for smaller files I am getting output file same as the input file.
FileInputStream excelFile = new FileInputStream(new File(pathToFile));
XSSFWorkbook xwb = new XSSFWorkbook(inputStream);
inputStream.close();
SXSSFWorkbook wb = new SXSSFWorkbook(xwb,100);
wb.setCompressTempFiles(true);
SXSSFSheet sh = (SXSSFSheet) wb.getSheetAt(0);
Iterator<Row> iterator = datatypeSheet.iterator();
int i=0;
while (iterator.hasNext()) { // Loop over each row
Row currentRow = iterator.next();
Cell cell = currentRow.createCell(currentRow.getLastCellNum());
cell.setCellType(Cell.CELL_TYPE_STRING);
if(currentRow.getRowNum() == 0)
cell.setCellValue("OUTPUT-COLUMN"); // set column header for the new column
else {
cell.setCellValue(list.get(i)); // list contains the output to populate in new column
i++;
}
}
FileOutputStream fos = new FileOutputStream(new File(pathToOutput));
wb.write(fos);
fos.close();
Using a db is not suitable in my use case and i want to avoid using a temporary data structure to hold data for writing due to memory constraint.
Is there a way to write in output workbook while streaming ? Here is the code that I am using to read using POI Streaming API
private class ExcelData implements SheetContentsHandler {
LinkedHashMap<Strin, String> rowMap;
public void startRow(int rowNum) {
}
public void endRow(int rowNum) {
// Process the row
// Handle write to output workbook ??
}
public void cell(String cellReference, String formattedValue,
XSSFComment comment) {
// Save current row in rowMap ( column name => cell value )
}
public void headerFooter(String text, boolean isHeader, String tagName)
{
}
}
It is not possible to add column to existing workbook using POI SXSSF. It only allows addition of new rows.
The only solution is to read the existing workbook and write to a new workbook with the added column.
To achieve this we can store the rows in a data structure or database in the endrow() method and then use the persisted data to write a new workbook.
I have an Excel spreadsheet that has the first sheet designated for the raw data. There are 3 more sheets that are coded to transform and format the data from the raw sheet. The fifth sheet has the final output.
How can I use Java:
load the data from the CSV file into the first sheet of the excel file?
save the data from the 5th sheet into the new CSV file.
Also, if the original CSV has thousands of rows, I assume the multi-sheet transformations would take some time before the 5th sheet gets all the final data - is there a way to know?
I would follow this approach:
Load the specific .csv file and prepare to read it with Java
Load the .xlsx file and change it according to your requirements and the data that you get from the .csv file. A small example of how an excel file is changed with Apache POI can be seen below:
try
{
HashMap<Integer, ArrayList<String>> fileData; // This for example keeps the data from the csv in this form ( 0 -> [ "Column1", "Column2" ]...)
// Working with the excel file now
FileInputStream file = new FileInputStream("Data.xlsx");
XSSFWorkbook workbook = new XSSFWorkbook(file); // getting the Workbook
XSSFSheet sheet = workbook.getSheetAt(0);
Cell cell = null;
AtomicInteger row = new AtomicInteger(0);
fileData.forEach((key, csvRow) ->
{
//Update the value of the cell
//Retrieve the row and check for null
HSSFRow sheetRow = sheet.getRow(row);
if(sheetRow == null)
{
sheetRow = sheet.createRow(row);
}
for (int i = 0; i < csvRow.size(); i++)
{
//Update the value of cell
cell = sheetRow.getCell(i);
if(cell == null){
cell = sheetRow.createCell(i);
}
cell.setCellValue(csvRow.get(i));
}
});
file.close();
FileOutputStream outFile =new FileOutputStream(new File("Data.xlsx"));
workbook.write(outFile);
outFile.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
After saving the .xlsx file, you can create the .csv file by following this question.
I am trying to update an existing Excel with Apache POI.
The thing is, I have an excel having in its 3rd column telephone numbers, and I want to correct them to the specific format using if-statements.
But I cannot write to the file.
Here is the code I am using:
public void readingExcel(String fileName) throws Exception {
try (FileInputStream file = new FileInputStream(new File(fileName))) {
HSSFWorkbook workbook = new HSSFWorkbook(file);
HSSFSheet sheet = workbook.getSheetAt(0);
Iterator<Row> rowIterator = sheet.iterator();
int counter = 0;
for (Row row : sheet) {
int columnIndex = 2;
row = CellUtil.getRow(counter, sheet);
Cell cell = CellUtil.getCell(row, columnIndex);
if (formatter.formatCellValue(cell).length() == 8)
cell.setCellValue("+216" + formatter.formatCellValue(cell));
if (formatter.formatCellValue(cell).length() == 11 && formatter.formatCellValue(cell).startsWith("216"))
cell.setCellValue("+" + formatter.formatCellValue(cell));
counter++;
}
FileOutputStream outFile =new FileOutputStream(new File(fileName));
workbook.write(outFile);
outFile.close();
}
}
And I am getting this error
org.apache.poi.poifs.filesystem.NotOLE2FileException: Invalid header signature; read 0x0000000000000000, expected 0xE11AB1A1E011CFD0 - Your file appears not to be a valid OLE2 document
at org.apache.poi.poifs.storage.HeaderBlock.<init>(HeaderBlock.java:181)
at org.apache.poi.poifs.storage.HeaderBlock.<init>(HeaderBlock.java:140)
at org.apache.poi.poifs.filesystem.NPOIFSFileSystem.<init>(NPOIFSFileSystem.java:302)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:398)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.<init>(HSSFWorkbook.java:379)
at excelapp.myClass.readingExcel(myClass.java:50)
at excelapp.myClass.<init>(myClass.java:41)
at excelapp.ExcelApp.main(ExcelApp.java:26)
The thing is that it is really important for today, and I am getting really stuck on updating the values of that column :-/ anyone has an idea? I think I'm writing the wrong way..
I have fetched the value from the textbox and stored in a string. Now i want to write this value stored in string into the column named as 'Username' in the excel file.
E.G: Fetched the Username from the textbox as 'Test1' and want to write this in the column 'Username' of the Excel. I am using POI to write excel file using Selenium.
hi please implement the logic like below
public static void writeExcel(String filePath,String fileName,String sheetName,String[] dataToWrite) throws IOException{
//Create a object of File class to open xlsx file
File file = new File(filePath+"\\"+fileName);
//Create an object of FileInputStream class to read excel file
FileInputStream inputStream = new FileInputStream(file);
Workbook Workbook = null;
//Find the file extension by spliting file name in substing and getting only extension name
String fileExtensionName = fileName.substring(fileName.indexOf("."));
//Check condition if the file is xlsx file
if(fileExtensionName.equals(".xlsx")){
//If it is xlsx file then create object of XSSFWorkbook class
Workbook = new XSSFWorkbook(inputStream);
}
//Check condition if the file is xls file
else if(fileExtensionName.equals(".xls")){
//If it is xls file then create object of XSSFWorkbook class
Workbook = new HSSFWorkbook(inputStream);
}
//Read excel sheet by sheet name
Sheet sheet = Workbook.getSheet(sheetName);
//Get the current count of rows in excel file
int rowCount = sheet.getLastRowNum()-sheet.getFirstRowNum();
//Get the first row from the sheet
Row row = sheet.getRow(0);
//Create a new row and append it at last of sheet
Row newRow = sheet.createRow(rowCount+1);
//Create a loop over the cell of newly created Row
for(int j = 0; j < row.getLastCellNum(); j++){
//Fill data in row
Cell cell = newRow.createCell(j);
cell.setCellValue(dataToWrite[j]);
}
//Close input stream
inputStream.close();
//Create an object of FileOutputStream class to create write data in excel file
FileOutputStream outputStream = new FileOutputStream(file);
//write data in the excel file
Workbook.write(outputStream);
//close output stream
outputStream.close();
}
Now call the above in main method like below
public static void main(String[] args) {
// TODO Auto-generated method stub
WebDriver driver = new FirefoxDriver();
driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
String valueToWrite = "test 1";
//Create an object of current class
WriteExcelFile objExcelFile = new WriteExcelFile();
//Write the file using file name , sheet name and the data to be filled
objExcelFile.writeExcel(System.getProperty("user.dir")+"\\src\\excelExportAndFileIO","ExportExcel.xlsx","ExcelDemo",valueToWrite);
}
You need to know column number of "Username" column in the excel sheet. Once you know that then it will be easy to write value of String that you captured from webpage. You can take below approach -
File excelFile = new File("C:\\path\\of\\excel\\file\\excel.xlsx");
String cellNo = 3; //column number of "UserName" column
String rowNo = 1; // row number
String userName = "Test1"; // username fetched from textbox
FileInputStream fis = new FileInputStream(excelFile);
XSSFWorkbook workbook = (XSSFWorkbook) WorkbookFactory.create(fis);
XSSFSheet sheet = workbook.getSheetAt(0);
Row row = sheet.getRow(rowNo);
row.createCell(cellNo).setCellValue(userName);
fis.close();
FileOutputStream fos = new FileOutputStream(excelFile);
workbook.write(fos);
fos.close();
This is very simple approach just for this purpose and is not generalized one for any other task.
You can take a look at simple script that reads from a excel sheet and writes back to same excel sheet using Apache POI, here.
Regards,
Punkaaj