I am using apache poi to extract data from excel sheet and trying to save extracted values in an array.
I am getting java.lang.NullPointerException error.
I searched about it, and apparently this exception triggered when you try to assign a value to an object whose value is null.
I tried to look up many example, but most example codes just print out cell value. I want to save them in an array to perform some calculation.
package exceltotext;
import java.io.*;
import java.lang.*;
import java.util.*;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.FormulaEvaluator;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class convert {
#SuppressWarnings("null")
public static void main(String[] args) throws IOException {
double [] modify = null ;
FileInputStream fs = new FileInputStream(new File ("Book1.xlsx"));
XSSFWorkbook wb = new XSSFWorkbook(fs);
XSSFSheet sheet = wb.getSheetAt(0);
FormulaEvaluator formulaevaluater = wb.getCreationHelper().createFormulaEvaluator();
for (Row row:sheet)
{
int num = 0;
for(Cell cell : row){
switch (formulaevaluater.evaluate(cell).getCellType())
{
case Cell.CELL_TYPE_NUMERIC:
modify [num] = ( cell.getNumericCellValue());
num += num;
}
System.out.println(modify[num]);
}
}
}
}
Your modify array is null so num += num; will give you NPE. You need to create this array with for an egzample double [] modify = new double[1000]; instead of double [] modify = null ;
I think, first you need to define the rows, from where you are trying to extract the values.
Apache Poi have option for row i.e XSSFRow.
PS i would personally recommend HSSF instead of XSSF , hence HSSF is for new version of excel. You need to change the file extension name to use in HSSF if the same document is being used by XSSF (Cause of Version Incompatibility).
Related
I'm trying to remove a row in a excel sheet using java.
But my code isn't removing anything.
This is my code for removing the last row.
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.apache.poi.ss.usermodel.Sheet;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
final String filepath = "data-DB.xlsx";
File workbookFile = new File(filepath);
FileInputStream in = new FileInputStream(workbookFile);
Workbook database = WorkbookFactory.create(in);
Sheet sheet = database.getSheet("Users");
int lastRow = sheet.getLastRowNum();
Row row = sheet.getRow(lastRow);
sheet.removeRow(row);
}
}
This line should get the row
Row row = sheet.getRow(lastRow);
This should remove the row.
sheet.removeRow(row);
What am I doing wrong?
The documentation for getLastRowNum says :
Gets the last row on the sheet Note: rows which had content before and
were set to empty later might still be counted as rows by Excel and
Apache POI, so the result of this method will include such rows and
thus the returned value might be higher than expected!
So most probably you'll get getting a row number which is empty already and you are trying to remove that, and you'r seeing that removeRow is not working.
Print or debug the value of lastRow to fix the error
I am trying to create an Excel sheet that contains an Excel table using Java with the Apache POI library but I couldn't get a result file that is readable by Microsoft Excel 2016 (Office 365). This is my code:
import org.apache.poi.ss.util.AreaReference;
import org.apache.poi.ss.util.CellReference;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
class Scratch {
public static void main(String[] args) throws IOException {
XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet sheet = workbook.createSheet("Table Sheet");
XSSFRow row0 = sheet.createRow(0);
row0.createCell(0).setCellValue("#");
row0.createCell(1).setCellValue("Name");
XSSFRow row1 = sheet.createRow(1);
row1.createCell(0).setCellValue("1");
row1.createCell(1).setCellValue("Foo");
XSSFRow row2 = sheet.createRow(2);
row2.createCell(0).setCellValue("2");
row2.createCell(1).setCellValue("Bar");
AreaReference area = workbook.getCreationHelper().createAreaReference(
new CellReference(row0.getCell(0)),
new CellReference(row2.getCell(1))
);
sheet.createTable(area);
try(FileOutputStream file = new FileOutputStream(new File("workbook.xlsx"))) {
workbook.write(file);
}
}
}
The code runs fine but when I open the output file in Excel I get a message that the file has unreadable content.
I have tried running the official sample and the result is the same. The official sample can be found here: https://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/CreateTable.java
I need to know the minimum code required to get a readable table.
I am using version 4.0.0 of Apache POI with Oracle JavaSE JDK 1.8.0_172 on Windows 10.
Not sure what happens with the "official sample" codes always. They seems not even be tested.
The CreateTable uses XSSFTable table = sheet.createTable(reference); which creates a table having 3 columns as given from the area reference. But all of those have id 1, so we need repairing. And of course the columns should not be created again then.
So repaired sample code would be:
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.AreaReference;
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 org.apache.poi.xssf.usermodel.XSSFTable;
import org.apache.poi.xssf.usermodel.XSSFTableStyleInfo;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
/**
* Demonstrates how to create a simple table using Apache POI.
*/
public class CreateTable {
public static void main(String[] args) throws IOException {
try (Workbook wb = new XSSFWorkbook()) {
XSSFSheet sheet = (XSSFSheet) wb.createSheet();
// Set which area the table should be placed in
AreaReference reference = wb.getCreationHelper().createAreaReference(
new CellReference(0, 0), new CellReference(2, 2));
// Create
XSSFTable table = sheet.createTable(reference); //creates a table having 3 columns as of area reference
// but all of those have id 1, so we need repairing
table.getCTTable().getTableColumns().getTableColumnArray(1).setId(2);
table.getCTTable().getTableColumns().getTableColumnArray(2).setId(3);
table.setName("Test");
table.setDisplayName("Test_Table");
// For now, create the initial style in a low-level way
table.getCTTable().addNewTableStyleInfo();
table.getCTTable().getTableStyleInfo().setName("TableStyleMedium2");
// Style the table
XSSFTableStyleInfo style = (XSSFTableStyleInfo) table.getStyle();
style.setName("TableStyleMedium2");
style.setShowColumnStripes(false);
style.setShowRowStripes(true);
style.setFirstColumn(false);
style.setLastColumn(false);
style.setShowRowStripes(true);
style.setShowColumnStripes(true);
// Set the values for the table
XSSFRow row;
XSSFCell cell;
for (int i = 0; i < 3; i++) {
// Create row
row = sheet.createRow(i);
for (int j = 0; j < 3; j++) {
// Create cell
cell = row.createCell(j);
if (i == 0) {
cell.setCellValue("Column" + (j + 1));
} else {
cell.setCellValue((i + 1.0) * (j + 1.0));
}
}
}
// Save
try (FileOutputStream fileOut = new FileOutputStream("ooxml-table.xlsx")) {
wb.write(fileOut);
}
}
}
}
Btw.: My code from How to insert a table in ms excel using apache java poi works as well using apache poi 4.0.0. The sheet.createTable() is deprecated. So do using XSSFTable table = sheet.createTable(null); instead. Because the area as well as all other things is set using low level classes. Not even more code than the new example though.
Please find the attached code snippet and please help me to proceed with this. I am trying to read data from one excel and then write the same to another excel , while trying to write the file it's stopping the code. When I tried debugging I could see that value is properly fetched but write is not working.
package Export;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
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.xssf.usermodel.XSSFWorkbook;
public class TestExport
{
XSSFWorkbook xlsxworkbook;
HSSFWorkbook xlsworkbook;
XSSFWorkbook xlsxworkbook1;
HSSFWorkbook xlsworkbook1;
Sheet sheet;
Sheet sheet1;
TestExport(){
xlsxworkbook=null;
xlsworkbook=null;
sheet=null;
xlsxworkbook1=null;
xlsworkbook1=null;
sheet1=null;
}
public void readExcel(String filePath,String fileName,String sheetName,String filePath1,String fileName1,String sheetName1)
{
try{
FileInputStream fs=new FileInputStream(new File("C:\\Users\\Susmitha-Phases\\Desktop\\TestWorkbook.xlsx"));
FileOutputStream fi=new FileOutputStream(new File("C:\\Users\\Susmitha-Phases\\Desktop\\TestWorkbook1.xlsx"));
fs.toString();
if(fileName.toLowerCase().endsWith("xlsx")){
xlsxworkbook = new XSSFWorkbook(fs);
sheet=xlsxworkbook.getSheet(sheetName);
xlsxworkbook1 = new XSSFWorkbook();
sheet1=xlsxworkbook.getSheet(sheetName1);
}
else{
xlsworkbook=new HSSFWorkbook(fs);
sheet=xlsworkbook.getSheet(sheetName);
xlsworkbook1=new HSSFWorkbook();
sheet1=xlsworkbook.getSheet(sheetName1);
}
int rowCount = sheet.getLastRowNum()-sheet.getFirstRowNum();
//Create a loop over all the rows of excel file to read it
for (int i = 0; i < rowCount+1; i++)
{
Row row = sheet.getRow(i);
Row row1=sheet1.getRow(i);
//Create a loop to print cell values in a row
for (int j = 0; j < row.getLastCellNum(); j++)
{
String temp= row.getCell(j).getStringCellValue();
row1.createCell(i).setCellValue(temp);
//Print Excel data in console
System.out.print(row1.getCell(j).getStringCellValue()+"|| ");
xlsworkbook.write(fi);
//System.out.print(row.getCell(j).getStringCellValue()+"|| ");
}
}
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
public static void main(String[] args) throws IOException{
//Create an object of ReadGuru99ExcelFile class
TestExport objExcelFile = new TestExport();
//Prepare the path of excel file
String filePath = System.getProperty("C:\\Users\\Susmitha-Phases\\Desktop\\TestWorkbook.xlsx");
String filePath1 = System.getProperty("C:\\Users\\Susmitha-Phases\\Desktop\\TestWorkbook1.xlsx");
//Call read file method of the class to read data
objExcelFile.readExcel(filePath,"TestWorkbook.xlsx","Sheet1",filePath1,"TestWorkbook1.xlsx","Sheet1");
}
}
There are some problem with your code it possible throw null pointer exception
You never created the instance for xlsworkbook in your class when the file type xlsx and trying to write the file . which is wrong will throw definitely null pointer exception. so You must change the logic while writing which file type should be write . Probably you can check file type and write the file.
I need to write to an excel cell a very large numbers(>91430000000000000000)
The issue is that max value for cell is 9143018315613270000, and all values which is larger - would be replaced by max value.
This issue will simply resolved by hands if an apostrophe is added to an number, for example '9143018315313276189
But how to the same trick via apache POI? I have follow code:
attrId.setCellValue(new XSSFRichTextString('\'' + value.getId().toString()));
But it doesn't work:
Here the first row haven't any apostrophe at all, second one is written by hands and it is the result I'm looking for. Third is a result of my code. I also tried to use setCellValue which takes double and String, both of them doesn't help me ether.
So, here goes the question: How to write in excel a very large numbers via apache POI?
Set the cell style first
DataFormat format = workbook.createDataFormat();
CellStyle testStyle = workbook.createCellStyle();
testStyle.setDataFormat(format.getFormat("#"));
String bigNumber = "9143018315313276189";
row.createCell(40).setCellStyle(testStyle);
row.getCell(40).setCellValue(bigNumber);
Can you set the Cell type and see what happens. Or if you have already set that then please post your code so that others look at it.
cell.setCellType(Cell.CELL_TYPE_STRING);
Please refer to the question in here for details on how to set string value to cell How can I read numeric strings in Excel cells as string (not numbers) with Apache POI?
I did the following sample and worked for me (poi-3.1.3)
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
public class WriteToExcel {
public static void main(String[] args) throws IOException {
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet("Sample sheet");
Row row = sheet.createRow(0);
Cell cell = row.createCell(0);
cell.setCellType(Cell.CELL_TYPE_STRING);
cell.setCellValue("91430183153132761893333");
try {
FileOutputStream out =
new FileOutputStream(new File("C:\\test_stackoverflow\\new.xls"));
workbook.write(out);
out.close();
System.out.println("Excel written successfully..");
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I am trying the this testfile with the Apache POI API (current version 3-10-FINAL). The following test code
import java.io.FileInputStream;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class ExcelTest {
public static void main(String[] args) throws Exception {
String filename = "testfile.xlsx";
XSSFWorkbook wb = new XSSFWorkbook(new FileInputStream(filename));
XSSFSheet sheet = wb.getSheetAt(0);
System.out.println(sheet.getFirstRowNum());
}
}
results in the first row number to be -1 (and existing rows come back as null). The test file was created by Excel 2010 (I have no control over that part) and can be read with Excel without warnings or problems. If I open and save the file with my version of Excel (2013) it can be read perfectly as expected.
Any hints into why I can't read the original file or how I can is highly appreciated.
The testfile.xlsx is created with "SpreadsheetGear 7.1.1.120". Open the XLSX file with a software which can deal with ZIP archives and look into /xl/workbook.xml to see that. In the worksheets/sheet?.xml files is to notice that all row elements are without row numbers. If I put a row number in the first row-tag like <row r="1"> then apache POI can read this row.
If it comes to the question, who is to blame for this, then the answer is definitely both Apache Poi and SpreadsheetGear ;-). Apache POI because the attribute r in the row element is optional. But SpreadsheetGear also because there is no reason not to use the r attribute if Excel itself does it ever.
If you cannot get the testfile.xlsx in a format which can Apache POI read directly, then you must work with the underlying objects. The following works with your testfile.xlsx:
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.InputStream;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTWorksheet;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTSheetData;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow;
import java.util.List;
class Testfile {
public static void main(String[] args) {
try {
InputStream inp = new FileInputStream("testfile.xlsx");
Workbook wb = WorkbookFactory.create(inp);
Sheet sheet = wb.getSheetAt(0);
System.out.println(sheet.getFirstRowNum());
CTWorksheet ctWorksheet = ((XSSFSheet)sheet).getCTWorksheet();
CTSheetData ctSheetData = ctWorksheet.getSheetData();
List<CTRow> ctRowList = ctSheetData.getRowList();
Row row = null;
Cell[] cell = new Cell[2];
for (CTRow ctRow : ctRowList) {
row = new MyRow(ctRow, (XSSFSheet)sheet);
cell[0] = row.getCell(0);
cell[1] = row.getCell(1);
if (cell[0] != null && cell[1] != null && cell[0].toString() != "" && cell[1].toString() != "")
System.out.println(cell[0].toString()+"\t"+cell[1].toString());
}
} catch (InvalidFormatException ifex) {
} catch (FileNotFoundException fnfex) {
} catch (IOException ioex) {
}
}
}
class MyRow extends XSSFRow {
MyRow(org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow row, XSSFSheet sheet) {
super(row, sheet);
}
}
I have used:
org.openxmlformats.schemas.spreadsheetml.x2006.main.CTWorksheet
org.openxmlformats.schemas.spreadsheetml.x2006.main.CTSheetData
org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow
Which are part of the Apache POI Binary Distribution poi-bin-3.10.1-20140818 and there are within poi-ooxml-schemas-3.10.1-20140818.jar
For a documentation see http://grepcode.com/snapshot/repo1.maven.org/maven2/org.apache.poi/ooxml-schemas/1.1/
And I have extend XSSFRow, because we can't use the XSSFRow constructor directly since it has protected access.