Writing CSV File from Database Generates Null Pointer

[Scott Florez]

Hi everyone. I am using the code below to write the contents of a SQL database to a CSV file. However, every time I run it, regardless of the database content, I get a null pointer error somewhere in a record in the 800s range (and the file write stops). Since it produces the same error with different data, I'm pretty sure that the problem is not in the database content. Can you take a look and see if you have any ideas? Thanks!

import java.io.*;
import java.sql.ResultSet;
import javax.swing.JFileChooser;
 
/**
Exports all search results to CSV file.
*/
public class WriteDump
{
 
    public WriteDump()
    {
        try
        {
            JFileChooser jfilechooser = new JFileChooser();
           ExampleFileFilter filter = new ExampleFileFilter();
    filter.addExtension("xls");
    filter.setDescription("XLS Files");
jfilechooser.setFileFilter(filter);
    int returnVal = jfilechooser.showSaveDialog(SearchMenu.dump);
    
if(returnVal == JFileChooser.APPROVE_OPTION) 
{
File file = jfilechooser.getSelectedFile();
 
            BufferedWriter bufferedwriter = new BufferedWriter(new FileWriter(file.getPath()+".xls"));
            int j = 1;
            MainMenu.rs.beforeFirst();
            bufferedwriter.write("First Name\tLast Name\tCompany\tTitle\tDepartment\tClass\tPhone\tCity\tState\tPrefix\tPhone2\tAddress\tAddress2\tZIP\tCounty\tRegion\tEmail\tFax\n");
            
if(MainMenu.rs != null) while(MainMenu.rs.next()) 
                {
                    for(int k = 0; k < 18; k++)
                    {
                        bufferedwriter.write((new StringBuilder()).append(MainMenu.rs.getString(j).trim()).append("\t").toString());
                        j++;
                    }
 
                    bufferedwriter.write("\n");
                    j = 1;
                }
            
bufferedwriter.close();
}
        }
        
catch(Exception exception)
        {
            System.out.println((new StringBuilder()).append("ERROR: ").append(exception).toString());
        }
    }
}

[Paul Clapham]

Run it again, and this time look carefully at the stack trace. It will tell you the line number where the error occurs. Look there.

However, having said that, if you are going to test whether MainMenu.rs is null, surely you should do that before this line of code:

MainMenu.rs.beforeFirst();

[Scott Florez]

This line is causing the null pointer:

bufferedwriter.write((new StringBuilder()).append(MainMenu.rs.getString(j).trim()).append("\t").toString());

Also, the null pointer is not always in a record in the 800s range, as I just produced the error in the 500s range.
[ April 10, 2007: Message edited by: Scott Florez ]