Make android app in android studio based on requirements specified

I have two modules: About first module, it is a video calling and streaming app. Written in android studio by using java language. It is showing an error known as "cannot find symbol notnull", I tried all available solutions in the internet and youtube, so need an expert to take up this task. Second module is in python, it recognizes the face from the video, detects the facial expression, head movements, blink counts, and these data should be sent as text or in table format to the host of the meeting. partial code is available. Salary will be 2,000 rupees, will be given online.