Re: Structs and null pointer exceptions

>>>>> jamesb457@[EMAIL PROTECTED]
 (J) wrote:

>J> I have an IDL looking something like this
>J> module LMS
>J> {

>J>   struct Alarm
>J>   {
>J>     string sensor;
>J>     string zone;
>J>   };

>J>   interface LMSIF
>J>   {
>J>     void raise_alarm(in Alarm aReading);
>J>     void send_alarm_to_rmc(in string alarm);
>J>     string test_case();
>J>   };
>J> };

>J> and a java file looking something like:

>J> class LMSServant extends _LMSIFImplBase
>J> {
>J>    Alarm al;
>J>    //functions here
>J>   public LMSServ()
>J>   {
>J>       //this line causes the problem.
>J>       al.sensor = "Sensor 1";
>J>   }

>J> }

>J> The problem i'm having is when i try to modify or write to the Alarm
>J> struct i get a NullPointerException every time.
>J> Am i doing something wrong?

yes. You only declare the Alarm variable al, but you don't reserve any
memory for it. It initializes with null. In Java Corba structs are cl*****
and you have to create an instance with new. In contrast to C and C++
where
structs get memory automatically.

So Alarm al = new Alarm(); should solve it I think.
-- 
Piet van Oostrum <piet@[EMAIL PROTECTED]
>
URL: http://www.cs.uu.nl/~piet
[PGP 8DAE142BE17999C4]
Private email: piet@[EMAIL PROTECTED]