This post will get a solution for an error bash: add-apt-repository: command not found while using the add-apt-repository command in both Debian or Ubuntu

often install the software on Ubuntu or Debian is to use PPA (Personal package active). the structure of use PPA in Linux

$ sudo add-apt-repository ppa:some/ppa

The package add-apt-repository is not installed on your system, which means need to install software-properties-common package,

$ apt-get install software-properties-common
$ apt-get update

Then you will try the command to install JAVA packages,
$ add-apt-repository -y ppa:webupd8team/java