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From Daniel John Debrunner <...@apache.org>
Subject Re: Returning NULL from a database-side Java function
Date Tue, 09 Oct 2007 16:01:15 GMT
Alan Burlison wrote:
> Rick Hillegas wrote:
> 
>> It is hard to say where the NullPointerException originates. Could you 
>> post a reproducible test case and the full stack trace from derby.log? 
> 
> Umm, it may be my bad, I have the following:
> 
>     public static int iGoBang() {
>         int pop = 0 == 0 ? 1 : null;
>         return pop;
>     }
> 
> Which compiles but blows up, whereas
> 
>     public static int iGoBang() {
>         return null;
>     }
> 
> won't even compile.  Because you can't assign null to a primitive type - 
> duh.  Which leaves 2 questions:
> 
> 1. Why does int pop = 0 == 0 ? 1 : null; even compile?

Maybe the compiler figures out that it's the same as pop = 1 so it 
discards the null? Seems like it shouldn't compile.

> 2. How *do* you return a database NULL from a function with a primitive 
> type as the return type? String isn't a primitive type.

You need to use the corresponding object type, in this case 
java.lang.Integer as the return type.

Dan.


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