Add interview for java skills

[ImanX]

No description provided.

[farhad]

Hey Iman,

Thanks for stepping up for contribution to this repo.
Gathering technical interview questions for Android, Java, and Kotlin can be a tedious task since you've got a lot to cover :). I really liked that you chose Java questions and I read all of them.

Here's what I'd like to share about your PR :

1. Regarding the OOP questions, I think you can add more items to cover different angles of it, like composition, inheritance, polymorphism, advantages and comparing it with structured and functional approaches.
   When in an interview, I personally dislike having to answer general prepackaged questions like "What is OOP?", firstly because I've to talk a lot to prove that I know the domain and secondly because any idiot can regurgitate a book of computer jargon !!
   Instead, I LOVE to face challenging questions that hit me in the face when asked. So I recommend you to be more comprehensive and inclusive with the questions.

2. The grammar structure is another thing that can be improved for this PR. Avoid using shorthand notations like "What diff" instead of "What's the difference between" :). Think of it as a grammar and vocab practice and seek help or self-train of language skills.
   Moreover, do try to be creative in Java questions and once more, avoid general questions. They can be easily googled :)

3. I noticed that you tried to ask questions about different subjects in Java. The Java language is a huge topic and If you look at Java Ref books, you'll see they're almost 1K pages and the interesting thing's that almost nobody reads them :).
   What I'm trying to say is that you don't have to create a questionnaire that comprises Java, in one go. You can and I think you should create multiple shortlists for important things like Threading, IO, Generics, Design Patterns, ...

Finally, I'd like to appreciate your involvement and definitely want to hear more from you and your work.