[rules-users] Simple Global Error !!

[Wolfgang Laun]

It may not be quite so simple as that - using int to illustrate a
problem occuring with Integer is misleading.

An Integer is an immutable object.
   Integer a = Integer.valueOf( 42 );
   a += 1
You'll certainly still have an Integer object available via 'a', but
it's *not* the one containing 42 any more - that's already in the
garbage.

The situation is aggravated by the fact that a 'global' is stored in a
sort of container and this container is not directly accessible for
effecting a change, only via setGlobal().

-W

On 16/07/2012, Esteban Aliverti <esteban.aliverti at gmail.com> wrote:
> Let's say you have this method in a java class:
>
> public void addOne(int number){
>    number = number +1;
> }
>
>
> And let's say you want to invoke that method from another method in the
> same (or a different. It doesn't matter) object:
>
> int number = 0;
> this.addOne(number);
> System.out.println("Number= "+number);
>
> What is the output of the code above? Figure out that and you will figure
> out what is happening with your global.
>
> Best Regards,
>
> XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> Esteban Aliverti
> - Blog @ http://ilesteban.wordpress.com
>
>
> On Mon, Jul 16, 2012 at 11:53 AM, abhinay_agarwal <
> abhinay_agarwal at infosys.com> wrote:
>
>> global java.lang.Integer count
>>
>>
>> rule "rule1"
>> agenda-group "1"
>> when
>>        //smething
>> then
>>       count=0;
>>       System.out.println(count); // output is 0
>>       count = count +1;
>>       System.out.println(count); // output is 1
>>       drools.setFocus("2");
>> end
>>
>>
>> rule "rule2"
>> agenda-group "2"
>> when
>>        //smething
>> then
>>       System.out.println(count); // output is 0
>> end
>>
>> in the rule2, the value of the global variable "count" must be 1, why m i
>> getting it as zero ?
>>
>> --
>> View this message in context:
>> http://drools.46999.n3.nabble.com/Simple-Global-Error-tp4018697.html
>> Sent from the Drools: User forum mailing list archive at Nabble.com.
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>