Como instalar o Java 8 no Ubuntu 20.04
sudo apt update
sudo apt install openjdk-11-jdk
sudo apt update
sudo apt install openjdk-8-jdk
BlueMoon
sudo apt update
sudo apt install openjdk-11-jdk
sudo apt update
sudo apt install openjdk-8-jdk
sudo apt-get install openjdk-11-jdk
sudo apt-get update && sudo apt-get upgrade