How to get the class reference name in Java using reflection

I have a json like

"Someform":"Somebuilder"

.I have parsed the json and retrieved value for Someform as below.

String formBuilder = pageJson.getString("Someform");

Now formBuilder contains "Someform" reference .

How do I get the class name for this i.e Someformclass . I used reflection like below

String className = formBuilder.getClass().getSimpleName();

Above statement is giving me String class name not the someform class name since formBuilder is String class. How do I get the someform class name which is dynamic so that I can pass this as argument to

Class builderName = Class.forName(className);

and invoke the method in that class.To be more precise I need to get the class name for Someform like SomeForm.class instead of String class.

Any help would be appreciated . TIA.