No matter the type of a variable or whether it is inmutable or not, if you
reassign a variable inside a method you are not going to see that change
outside the method. Each method in java receives a copy of the variable
(pointing to the same object of course) we are passing. Changing the object
reference of the variable inside a method is not going to affect the
original variable.
@Abhinay, the truth is that Drools transforms the RHS of a rule is into a
java class. And, just like Wolfgang says, globals are stored in some kind
of Map, so you must use setGlobal() if you want to change the value of a
global in drools.
Best Regards,
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Esteban Aliverti
- Blog @
http://ilesteban.wordpress.com
On Mon, Jul 16, 2012 at 2:08 PM, Wolfgang Laun <wolfgang.laun(a)gmail.com>wrote:
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(a)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(a)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.
>> _______________________________________________
>> rules-users mailing list
>> rules-users(a)lists.jboss.org
>>
https://lists.jboss.org/mailman/listinfo/rules-users
>>
>
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