We can understand this from both the point of view of an employer and a student. If we first look at the employer side, then Python is highly recruited.

And if we look by the view of a student, then Java.

Let us elaborate on that. 

There is a huge industry of tech in the USA. There are many students that look forward to having a career in such industries by learning to program.

Java and Python are both such languages that students choose for their career advancement.

Students learning under OPT, get many job opportunities in the USA. OPT candidates in USA get hired in a huge mass under Java.

However, that does not mean that Python is not so famous but little less one can say. OPT resume database are filled with students with a good knowledge of programming languages. 

Students with an educational background in Python or Java are highly in demand. OPT job portals are the proof of that.

OPT candidates in USA are among many international candidates that are making their careers after learning Java.

The demand for Python language is seen among employers, that are offering OPT jobs in USA. So, employers are searching for Python learners.

There are both ways. Jobs for OPT students are in both languages. The demand of both the masses is different. 

OPT resume bank has the talent of both sides as the tech industry is growing in the USA. One can choose the language that is more in demand of their similar crowd. One can find many options in OPT jobs in USA.