8.2. Working With Globals

Procedure 8.1. Task

1. To start implementing globals into the Working Memory, declare a global in a rules file and back it up with a Java object:

   global java.util.List list

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2. With the Knowledge Base now aware of the global identifier and its type, you can call ksession.setGlobal() with the global's name and an object (for any session) to associate the object with the global:

   List list = new ArrayList();
   ksession.setGlobal("list", list);

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   Important

   Failure to declare the global type and identifier in DRL code will result in an exception being thrown from this call.
3. Set the global before it is used in the evaluation of a rule. Failure to do so results in a NullPointerException.