Re: Excel/POI - Here We Go Again

Can somebody please provide me with the URL where Scott Klement explains how
to use POI HSSF with RPG. Thanks in advance.

cheers,
Jake.

On 9/21/06, Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx> wrote:

> Strangely, the 'open' returns an address of ZERO for 'book' but does not
> halt. The exception occurs only when the HSSF_GETSHEET fails because the
> 'book' address is 0.

That's not strange at all.  In an earlier discussion someone (I thought it
was you, actually?) was trying to handle situations where hssf_open()
could fail.  I think he was trying to open a file that might not exist,
and wanted a way to handle the error properly.  My memory is fuzzy, but it
was something like that.

Hang on, I'll look up the message in the archives...  yes, it was you.
Here are the key messages in the thread where we discussed it.
http://archive.midrange.com/rpg400-l/200608/msg00733.html
http://archive.midrange.com/rpg400-l/200608/msg00745.html

I probably didn't tell you that I changed it, though..  my fault.  The
idea, though, is that instead of crashing (and taking the JVM down) when a
file can't be opened for some reason, it now returns *NULL.  Your program
and therefore check for that.

      if HSSF_open( '/path/to/myfile.xls' ) = *NULL;
           ErrMsg ='Unable to open Excel document';
           ShowErrorToUser(Errmsg);
           iter;  // try next document.
      endif;

The following part of your message is the REAL problem, the reason why
it's failing and therefore returning zero:

>   received Java exception
> "org.apache.poi.hssf.record.RecordFormatException:
>   Unable to construct record instance, the following" when calling
method
>   "<init>" with signature
>   "(Lorg.apache.poi.poifs.filesystem.POIFSFileSystem;)V" in class
>   "org.apache.poi.hssf.usermodel.HSSFWorkbook".

Excel documents are made up of specially formatted "records" (they aren't
database records in the manner that we're used to thinking of, but they
are a record of sorts.)

When the Java code (HSSF) is reading the file, it needs to create a new
Java record object to handle the record that it just loaded from the Excel
document.  However, for some reason it's unable to do that.

I would suspect that either it doesn't understand the format of the record
(maybe it's a feature that HSSF doesn't support) or there's a bug in the
Apache HSSF code.  Something like that.

Unfortunately, that's outside of my area of expertise.  You could try
upgrading POI to see if it's fixed in a newer version, or you might try
searching (Google) for the Java error to see if anyone else has
encountered it and found a workaround.
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