Since I am new to this, I'm not sure what I like more. I have also been self-teaching before this course but have not gotten deep into a particular language's fundamentals. I want to decide on a language and stick to it before I move to a new one after the first language is learned, but it is difficult deciding which language to start with. I want to develop medical software and medical mobile apps.
While I've seen many people recommend Java (and I agree with them), I think you can learn both. But it depends on how much time you got. I recommend you first learn Java. Then python will be easy to learn, and focus mainly on modules for graphs. The reason why I recommend to learn both is because python is much better and easier to code about statistical analysis. But again do this only if you have time to just learn them.
Sticking to a language before moving on is a common goal. However, in reality you are going to transition as you find languages that better suit you or your organization's requirements. Start with Java, not because it is optimal for your end goals, but because it will teach you what you like and dislike about programming and because your instructor is more familiar with it. That will give you a valuable perspective and allow you to make a more informed decision later.
There are many ways to solve problems in different languages, but the "best" language pragmatically is the one that you feel most comfortable using. In that respect, programming is like woodworking- you want to let the tool do the work. If there is another language that is "better" objectively but more difficult or confusing to you, you will counteract the anticipated benefits by having to struggle to write code.