Firstly, you need not have to learn a particular language. You just need to be expert in one Object Oriented Language and that's enough. That OOP's language can be C++, JAVA, or Python, that's your choice. 

Secondly, if you are planning to join banks, then JAVA would be a good choice to learn and that will be enough. You don't need to learn any other language.

If you are planning to learn Machine learning, then Pyton would be a good choice.

Just be fluent with one OPP's language and be clear about the OPP's concept, and you are done. You can surely clear any interview.

ALL THE BEST