In my free time, I love to try new programming language. Nowadays, almost everyone are using smartphone. So I guess now is the time to try mobile development. I will start with Android development as I think it's more easier to start with.
Although there's open source Java available (OpenJDK) and easily available to be installed using simple apt-get command, I prefer the Oracle version. This is pure my personal preference, without considering security, support, etc. You can use this guide to get Oracle Java 8 installed on Linux Mint 18.3 Sylvia. By the time of writing, the latest version of Oracle Java is version 8 update 171.