Linux/Ubuntu 16

Open JDK 11

JDK 11 Apt Install

sudo add-apt-repository ppa:linuxuprising/java
sudo apt update
sudo apt install oracle-java11-set-default

Didn't work for me, looks like they broke the repo!

JDK 11 Manual Install

curl -O https://download.java.net/java/GA/jdk11/9/GPL/openjdk-11.0.2_linux-x64_bin.tar.gz
tar zxvf openjdk-11.0.2_linux-x64_bin.tar.gz
sudo mv jdk-11* /usr/local/

sudo vim /etc/profile.d/jdk.sh

export JAVA_HOME=/usr/local/jdk-11.0.2
export PATH=$PATH:$JAVA_HOME/bin

source /etc/profile
java -version
  openjdk version "11.0.2" 2018-10-16
which java
  /usr/local/jdk-11.0.2/bin/java

Ref: https://computingforgeeks.com/how-to-install-java-11-on-ubuntu-18-04-16-04-debian-9/