How do I install Java for Ubuntu 20.04?
As taken from this list, you'll likely want to run:
sudo apt install openjdk-14-jdk
This will install the Java 14 JDK which will allow you to run Java programs and develop in Java. Remember that JDK 14 is not a "LTS" release - it will no longer be supported in September of 2020 (see the Oracle release roadmap for details).