Jmeter $__Random() with user defined variables - jmeter

Question

I have an issue I have been struggeling with for some time.
In my script I'm calculating a max and min value. I save it using:
int minWaitPregancy_acutall=0.2*maxWaitPregancyWait;
int maxWaitPregancy_acutall=0.8*maxWaitPregancyWait;
vars.putObject("minWaitPregancy_acutall", minWaitPregancy_acutall);
vars.putObject("maxWaitPregancy_acutall", maxWaitPregancy_acutall);
So far so good, it is saved and I can see it using the debugger.
Now I would like to use it in say a "Uniform Random timer".
I set the constant delay to 0 and in the Random Delay Maximum I try thing like:
${__Random(${__eval(vars.getObject("minWaitPregancy_acutall"))},${__eval(vars.get("maxWaitPregancy_acutall"))})}
For some reason that (and other variations, like skipping __eval) doesn't work I get variations of:
"java.lang.NumberFormatException: For input string: "vars.getObject("minWaitPregancy_acutall")""
So I guess I don't understand how to retrieve and use the data from the user defined variables. Any help??

Answer 1

As per Elements of Test Plan -> Execution Order
0. Configuration elements
1. Pre-Processors
2. Timers
3. Sampler
4. Post-Processors (unless SampleResult is null)
5. Assertions (unless SampleResult is null)
6. Listeners (unless SampleResult is null)
As per User Defined Variables documentation:
The User Defined Variables element lets you define an initial set of variables, just as in the Test Plan.
Note that all the UDV elements in a test plan - no matter where they are - are processed at the start.
It looks like you're using the wrong test element, if you want to calculate a random variable and save it you need to use a PreProcessor, for example User Parameters