sudo apt-get install / uninstall

1. java

//install 
$ sudo apt update
$ sudo apt install default-jre
$ sudo apt install default-jdk

//uninstall 
$ sudo apt-get autoremove default-jdk openjdk-11-jre

• how to unintall

  • https://stackoverflow.com/questions/23959615/how-to-remove-default-jre-java-installation-from-ubuntu