Null Pointer Exception when executing a Java software

[dtian.tyson]

Hi,

I am using a java software for my research. It was distributed as
class files. The software takes a text file and do some computation
then it outputs the results. For some text files, the software runs
normally. However, for 2 files, the software outputs
java.lang.NullPointerException. Both files are in the same format as
the others. I don't have the source code, so I can not see the
problem.

Does anyone knows what could be wrong with the code?

The software is a data mining tool called Keel: http://sci2s.ugr.es/keel/download.php

Many thanks,
David

 

[Patricia Shanahan]

Hi,

I am using a java software for my research. It was distributed as
class files. The software takes a text file and do some computation
then it outputs the results. For some text files, the software runs
normally. However, for 2 files, the software outputs
java.lang.NullPointerException. Both files are in the same format as
the others. I don't have the source code, so I can not see the
problem.

Does anyone knows what could be wrong with the code?

The software is a data mining tool called Keel: http://sci2s.ugr.es/keel/download.php

Unfortunately, NullPointerException for Java programs is a bit like "The
patient has no pulse" for humans. Without access to the body, all that
can be said is that the program broke on those inputs.

According to the web page "If you want to get the source code of the
Prototype, you only have notify us sending a mail to the address of the
administrators of the website.". Why not do that?

Patricia

 

[rossum]

Hi,

I am using a java software for my research. It was distributed as
class files. The software takes a text file and do some computation
then it outputs the results. For some text files, the software runs
normally. However, for 2 files, the software outputs
java.lang.NullPointerException. Both files are in the same format as
the others. I don't have the source code, so I can not see the
problem.

Does anyone knows what could be wrong with the code?

The software is a data mining tool called Keel: http://sci2s.ugr.es/keel/download.php

Many thanks,
David

Pick one of the two files, chop it in half and see which half crashes
the program. Repeat until you have a small file that crashes the
program. Look at that small file and see if you can see anything.

Patricia's suggestion is also a good one.

rossum

 

[Roedy Green]

For some text files, the software runs
normally. However, for 2 files, the software outputs
java.lang.NullPointerException. Both files are in the same format as
the others. I don't have the source code, so I can not see the
problem.

Use a decompiler to get some source to study. See
http://mindprod.com/jgloss/decompiler.html

also see
http://mindprod.com/jgloss/runerrormessages.html#NULLPOINTEREXCEPTION

 

[dtian.tyson]

Use a decompiler to get some source to study.  Seehttp://mindprod.com/jgloss/decompiler.html

also seehttp://mindprod.com/jgloss/runerrormessages.html#NULLPOINTEREXCEPTION

Thank you very much for all the help!

David