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Trying to query an sql statement from a java program.  RSS feed

 
rand Kirby
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I am trying to execute a query statement from my java program, but whenever I run it I get a nullpointerexeption on the Statement stmt = DBConnect.con.createStatement();. Does anyone know how to fix this?

 
Stephan van Hulst
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Well, I don't know what DBConnect is, but either it, or DBConnect.con is null. I can't really tell you more unless you say what DBConnect is.
 
rand Kirby
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This is DBConnect

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Stephan van Hulst
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Well there you go. You initialize con to null, and never set it to anything else. Remember that only one main() method is run when you start your application.

This is not a good design though. You shouldn't have one static connection that is accessible by the entire application. Instead, classes that need to interact with a database should have a constructor that takes a DataSource. The class can then open a new or pooled connection at the moment they need it:

Note also that you probably shouldn't get passwords hashes out of your database until you're going to authenticate a specific user.
 
It is sorta covered in the JavaRanch Style Guide.
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