As you may know, the Oracle Java 8 (stable) has been recently released, coming with a lot of changes and new features.
Due to the fact that the Java 8 installer is avalable via PPA, installing the software on Ubuntu 18.10 Cosmic Cuttlefish, Ubuntu 18.04 Bionic Beaver, Linux Mint, Elementary OS and other Ubuntu derivative systems is easy. All you need to do is add the PPA to your system, update the local repository index and install the oracle-java8-installer package. Like this:
$ sudo add-apt-repository ppa:webupd8team/java
$ sudo apt-get update
$ sudo apt-get install oracle-java8-installer
Optional, to remove Java, do:
$ sudo apt-get remove oracle-java8-installer