Why should you avoid investing much time learning Java ?
Java need to be compiled, which makes Java much less convenient than languages like Python. So, if you're a novice learning to code for the first time, Java is not a good language to start with.
Java is not the fastest. No, it's not pretty. No, it's not as much fun as some languages. But for most vertical apps, it's the best tool for the job.
Similarly, in I.T., as a noob, you are unlikely to find a good first job without knowing Java, C#, and/or C++. (Or, as a front-end programmer, you can focus on JavaScript.)
Kotlin is a statically-typed programming language that runs on the Java Virtual Machine and also can be compiled to JavaScript source code.If you already seen google I/O 2017 keynote session then you should know that in java there are 86 lines of code and in kotlin there is only 1 line of code do the same work,and this is very exciting .You can use kotlin and java simultaneously,there is no problem with that.If you love java and dont want to leave it then you can continue with it.Google has declared kotlin as a official language for Android . In java there are some of the issues are very critical to handle but in Kotlin its very easy.
Python is one of the most chosen programming languages to learn first for its wide use and simplicity. It is a great stepping stone to learning more complex programming languages and frameworks!
Advise :
If you want to work in building mobile applications, it is better to focus on learning kotlin after learning java basics because most of the android jobs require either kotlin or react. This wasn't the case 2 years ago.