Use json.dump function in Python to serialize
your object into json format
. Then use something like json.org library in Java to parse
this object into Java object, some example over here.
Mind that not every object might be serializable, in general data structures like dictionaries or lists are easily serializable, from your description it seems like you want to move an instance of an object from one program into another, which is not possible to be done automatically and requires human work in rewriting the code as instances of classes contain not only data but also functions (methods).
Good luck!