# RJB and Null: Fail: unknown method name

**URL:** <https://www.ruby-forum.com/t/rjb-and-null-fail-unknown-method-name/173485>\
**Category:** Ruby\
**Created:** [August 10, 2009, 12:07pm UTC](https://www.ruby-forum.com/t/rjb-and-null-fail-unknown-method-name/173485 "2009-08-10T12:07:33Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![reisswolf](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b38774/32.png) [@reisswolf](https://www.ruby-forum.com/u/reisswolf)\
**Post date:** [August 10, 2009, 12:07pm UTC](https://www.ruby-forum.com/t/rjb-and-null-fail-unknown-method-name/173485/1 "2009-08-10T12:07:33Z")

</div>

Hello,

I’m in trouble with the Ruby-Java-Bridge.

The Java code snippet is:  
KEMListEditor subConceptListKEM = kemConcept.getSubConcepts(null, null,  
Boolean.FALSE);

kemConcept.getSubConcepts has parameters:  
KEMAbstractConceptEditor.getSubConcepts(String arg0, String arg1,  
Boolean arg2)

I tried this in Ruby:  
subConceptListKEM = @concept.getSubConcepts(nil, nil, false)

and this  
subConceptListKEM =  
@concept.\_invoke(‘getSubConcepts’,‘Ljava.lang.String;Ljava.lang.String;Ljava.lang.Boolean’,"","",  
false)

The answer is always: “Fail: unknown method name”

I modified the call with:  
@jBoolean = Rjb::import(‘java.lang.Boolean’)  
tFalse=@jBoolean.getBoolean(“false”)  
subConceptListKEM = @concept.getSubConcepts(nil, nil, tFalse)

but it’s still the same error. I think it could be the “null”.

I replaced “nil” witch “” - same result.

Do you have any tip for me?

Greetings from Wolfram