Since Oracle does not provide a native Java installation package for Ubuntu Linux, we can install via distribution created by webupd8 on PPA repository for Java.
First, we need to add PPA and update repository.
$ sudo add-apt-repository ppa:webupd8team/java
$ sudo apt-get update
and then, we can install Java 8 package.
$ sudo apt install oracle-java8-installer
During installation process, there will be a prompt to accept Oracle Java license, just select OK then press Enter. Afterwards, Java is ready, you can verify via this command:
$ javac -version
javac 1.8.0_151
It will print out Java version installed.
