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Exception in thread "main" java.lang.NullPointerException

bram van gemert
Greenhorn

Joined: Oct 06, 2011
Posts: 4

Hi everybody Just wrote this script:


When I compile there are no errors.
But when i run i get this error:

Exception in thread "main" java.lang.NullPointerException
at Database.main(Database.java:29)


Dont understand why.
Tia,
Bram
Adam Cripps
Ranch Hand

Joined: Oct 01, 2011
Posts: 41

bram van gemert wrote:
Hi everybody Just wrote this script:


When I compile there are no errors.
But when i run i get this error:

Exception in thread "main" java.lang.NullPointerException
at Database.main(Database.java:29)


Dont understand why.
Tia,
Bram


Is line 25 meant to be a useless while? It looks odd to me at that point. Are you missing curly braces?
Matthew Brown
Bartender

Joined: Apr 06, 2010
Posts: 4343
    
    8

The notes variable is initialized in the constructor. But no Database object is ever instantiated, so notes is still null. It's a static variable - why are you initializing it in a constructor?
 
It is sorta covered in the JavaRanch Style Guide.
 
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