Null Instance Variables on Screenflow

Question

Hi,
I have some problems with instance variable of type BPM Objects in a Screenflow.
I always create automatic processes without user interaction, and on server side I have seen that it's not necessary to instantiate an instance variable. Moreover if within a method I write (I use the Java style syntax):
String a;
a.toString(); // just to call a method on a not-instantiated variable
everything works correctly, the "a" variable is automatically instantiated.
But it seems that in an automatic activity of a Screenflow it's different, I need to do the new also for Instance Variables.
Then, in the Screenflow I have an Instance Variable myObject of type MyObject that is a BPM Object. This object has an attribute myStrings that is an array of String.
To instantiate the instance variable I can write:
myObject = new MyObject();
But then I get a java.lang.*NullPointerException* when I call the extend method of its attribute myStrings to add a string.
Do you agree with me that on the Screenflow code it's necessary to instantiate the variables?
How can I instantiate an Array of String?
Thank you.

Answer 1

Thanks Daniel, I'm using ALBPM 6.0,
i know the line where I get the exception, I have a logMessage before and after each line of code, and then in the exception stack there is the PBL Method line indicated:
Caused by: java.lang.NullPointerException
     at xobject.Fuego__AutoGen__Screenflows__.__ScreenflowConJsp.automatic1(__ScreenflowConJsp.xcdl:*19*)
19 is the code line where I get the exception. In this line I have this:
myObject.myStrings.extend(arg1 : a);
but the null object is not the array, it's myObject that is an Instance Variable.
In ALBPM60_Studio_ReferenceGuide at chapter Programming Styles paragraph Java Programming Style there is:
This style emulates Java syntax and adds several features to match PBL expressions. These added features include:
• Output arguments
• Input and display statements
• Variable auto-initialization
In fact in my previuos BPM projects I have seen that is not necessary to istantiate the variables, both for Instance Variable and local variable declared within a method. In my previous post I did an example:
String a;
a.toString();
Usually this causes an Exception, but not in ALBPM methods.
My main question is: is it possible that this is true just for Server side methods and not for Screenflow methods? Because in my case I need to instantiate every Instance Variable of my Screenflow (for example the myObject instance variable) in an Automatic Activity I have put as first Activity of the flow.
Thanks again for your help.