NullPointerException generating 0 byte files

["Meike Reichle (RZ)" <mr...@rz.uni-hildesheim.de>]

Hi everyone,

I am rather new to POI, but I am planing to use it for a project,
so I decided to first test it a bit before actually starting using it
in a big scale.
But unfortunatelly I just don't get it to work properly. 
What I wanted to do is to open an existing file, add some values 
and write that in a new file. Opening seems to work, but then 
I am doing something wrong and I can't  really figure out what it is. 
The class compiles without errors, but when I try to execute it, 
it throws three NullPointerExceptions and generates a new file with 
the size of 0 bytes. 

It's probably a rather dumb newbie mistake I did. But since I am still 
trying to understand the concept of  POI I'd be really glad if someone 
had a hint or some enlightening words for me.

Thanks in advance,
Meike


Here's my complete testing class: 


import java.io.*;
import org.apache.poi.poifs.filesystem.*;
import org.apache.poi.hssf.dev.*;
import org.apache.poi.hssf.eventmodel.*;
import org.apache.poi.hssf.model.*;
import org.apache.poi.hssf.record.*;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.*;

public class ExcelInterface 
{
     
    //opening an existing file
     public static HSSFWorkbook openFile()
     {
      try
      {
           FileInputStream in = new FileInputStream(Pfade.excel);
           POIFSFileSystem fs = new POIFSFileSystem(in);
           HSSFWorkbook wb = new HSSFWorkbook(fs);
           return wb;
      }
      catch(Exception e)
      {
           System.out.println(e);
      } 
      return null;
     }
 

    //write in some values
     public static HSSFWorkbook fill()
     {
      try 
      {
           HSSFWorkbook wb = openFile();
           HSSFSheet sheet = wb.getSheetAt(1);
           HSSFRow row = sheet.getRow(0);
           HSSFCell cell1 = row.getCell((short)1);
           HSSFCell cell2 = row.getCell((short)2);
   
           cell1.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
           cell2.setCellType(HSSFCell.CELL_TYPE_STRING);
           cell1.setCellValue(15);
           cell2.setCellValue("test :-)");
      }
      catch(Exception e)
      {
           System.out.println(e);
      } 
      return null;
     }
 


    //Save it to a new file
     public static void closeFile()
     {
      try
      {   
           HSSFWorkbook wb = fill();
           FileOutputStream out = new FileOutputStream(Pfade.excel2);
           wb.write(out);
           out.close();
      }
      catch(Exception e)
      {
           System.out.println(e);
      }
     }
 

 public static void main(String args[])
 {  
  openFile();
  fill();
  closeFile();
 }
 
}//end of class

Re: NullPointerException generating 0 byte files

[Glen Stampoultzis <gs...@iinet.net.au>]

It's probably something in the spreadsheet that is causing the problem.  I 
suggest you open a bug in bugzilla and attach the spreadsheet.

Regards,

Glen


At 12:32 AM 31/03/2003, you wrote:
>Hi everyone,
>
>I am rather new to POI, but I am planing to use it for a project,
>so I decided to first test it a bit before actually starting using it
>in a big scale.
>But unfortunatelly I just don't get it to work properly.
>What I wanted to do is to open an existing file, add some values
>and write that in a new file. Opening seems to work, but then
>I am doing something wrong and I can't  really figure out what it is.
>The class compiles without errors, but when I try to execute it,
>it throws three NullPointerExceptions and generates a new file with
>the size of 0 bytes.
>
>It's probably a rather dumb newbie mistake I did. But since I am still
>trying to understand the concept of  POI I'd be really glad if someone
>had a hint or some enlightening words for me.
>
>Thanks in advance,
>Meike
>
>
>Here's my complete testing class:
>
>
>import java.io.*;
>import org.apache.poi.poifs.filesystem.*;
>import org.apache.poi.hssf.dev.*;
>import org.apache.poi.hssf.eventmodel.*;
>import org.apache.poi.hssf.model.*;
>import org.apache.poi.hssf.record.*;
>import org.apache.poi.hssf.usermodel.*;
>import org.apache.poi.hssf.util.*;
>
>public class ExcelInterface
>{
>
>     //opening an existing file
>      public static HSSFWorkbook openFile()
>      {
>       try
>       {
>            FileInputStream in = new FileInputStream(Pfade.excel);
>            POIFSFileSystem fs = new POIFSFileSystem(in);
>            HSSFWorkbook wb = new HSSFWorkbook(fs);
>            return wb;
>       }
>       catch(Exception e)
>       {
>            System.out.println(e);
>       }
>       return null;
>      }
>
>
>     //write in some values
>      public static HSSFWorkbook fill()
>      {
>       try
>       {
>            HSSFWorkbook wb = openFile();
>            HSSFSheet sheet = wb.getSheetAt(1);
>            HSSFRow row = sheet.getRow(0);
>            HSSFCell cell1 = row.getCell((short)1);
>            HSSFCell cell2 = row.getCell((short)2);
>
>            cell1.setCellType(HSSFCell.CELL_TYPE_NUMERIC);
>            cell2.setCellType(HSSFCell.CELL_TYPE_STRING);
>            cell1.setCellValue(15);
>            cell2.setCellValue("test :-)");
>       }
>       catch(Exception e)
>       {
>            System.out.println(e);
>       }
>       return null;
>      }
>
>
>
>     //Save it to a new file
>      public static void closeFile()
>      {
>       try
>       {
>            HSSFWorkbook wb = fill();
>            FileOutputStream out = new FileOutputStream(Pfade.excel2);
>            wb.write(out);
>            out.close();
>       }
>       catch(Exception e)
>       {
>            System.out.println(e);
>       }
>      }
>
>
>  public static void main(String args[])
>  {
>   openFile();
>   fill();
>   closeFile();
>  }
>
>}//end of class
>
>
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----
Glen Stampoultzis
gstamp@iinet.net.au
http://members.iinet.net.au/~gstamp/glen/