Getting the local variables of a method

Hi,
 
I have been trying to get the local variables in a method but I don't see anything returned. I am using the following snippet.

LocalVariable lv[];
LocalVariableTable lvt;
lvt=mt.getLocalVariableTable(); //mt is a method  object
lv=lvt.getLocalVariableTable();
 
I don't get anything back in the lv array. Can anyone advise if this is the correct approach or if there is a better approach?

Thanks,
 Muthu