Android : Using DatePickerDialog with jnius

I recently tried to create an Android DatePickerDialog with jnius, but apparently did not manage to do it.

from jnius import autoclass
from android.runnable import run_on_ui_thread

context = autoclass("org.renpy.android.PythonActivity").mActivity
dialog = autoclass("android.app.DatePickerDialog")

@run_on_ui_thread
def run() :
    callback = dialog.OnDateSetListener()
    dialog(context, callback, 2000, 1, 1).show()

run()

How do I get it to work?