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NULL pointer exception.

sunil khandelwal
Greenhorn

Joined: Aug 02, 2010
Posts: 5
Hi,

I am very new to servlet.

I made a class to connect servlet to database bt i m getting this error.




my servlet class GetData.java is:-


and my database connection class Mysql_connection.java code is :-


please tell me solution ASAP


Thanks in advance.>
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14687
    
  16

please tell me solution ASAP

Please EaseUp and UseRealWords.


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sunil khandelwal
Greenhorn

Joined: Aug 02, 2010
Posts: 5
k.

ya next time i will do.

by ASAP my means as soon as possible.
Nicola Garofalo
Ranch Hand

Joined: Apr 10, 2010
Posts: 308
You do not initialize Connection object, that's why you are receiving a NullPointerException

I can't see any call to the method that initializes the Connection object.



Call method connection before calling the method query


Bye,
Nicola
Christophe Verré
Sheriff

Joined: Nov 24, 2005
Posts: 14687
    
  16

Nicola Garofalo wrote:I can't see any call to the method that initializes the Connection object.

Line 36
Ananth Chellathurai
Ranch Hand

Joined: Nov 21, 2007
Posts: 349

Is your connection url and parameters valid?


Ananth Chellathurai [Walk on software]
Nicola Garofalo
Ranch Hand

Joined: Apr 10, 2010
Posts: 308
Line 36...Great. Now i see it
Steven Schwab
Greenhorn

Joined: May 25, 2010
Posts: 9
In lines 35-43 of GetData, you're catching any exceptions that DriverManager.getConnection() might be throwing and just printing out stack traces.

If DriverManager.getConnection() throws an exception (and you ignore it like you are now), then Mysql_connection.connection will still be null when you try to use it in query().

Are any stack traces being printed out to the console or the log files?
subhash kumar
Ranch Hand

Joined: Jul 14, 2010
Posts: 63
your exception catching process is not giving you the enough information about exactly where the problem is.
every where you have used throws clause
i think first catch the exception using the try/catch block and then throw the same exception in the catch block
for example:



this will give you great advantages like debugging at development time.


Please correct me if i am wrong at any place(in this concept).

Subhash Kumar
Attitude is everything
Md Haidar Ali Khan
Greenhorn

Joined: Feb 18, 2010
Posts: 12
Christophe Verré wrote:
please tell me solution ASAP

Please EaseUp and UseRealWords.

Dear
you check out your connection Object. Might be that no connect propery.
Regards,
MD. Haidar Ali Khan
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: NULL pointer exception.