In Oracle ADF, PPR implementation is quite simple. The above scenario can be achieved by the following way ->
For this we can make the ‘AutoSumbit’ property of "first selectOneChoice" to “TRUE” . Now write the proper code in the value change event code of the "first selectOneChoice". This code must contain the value update codes for "second selectOneChoice". Copy the Unique id of "first selectOneChoice" i.e. selectOneChoice1 and paste in the partial trigger property of the "second selectOneChoice". That's it. The second combo box values will be updated automatically depending first combobox.