How to Install IntelliJ IDEA on Ubuntu 18.10 Cosmic Easy Visual-Guide

3. Expand IntelliJ IDEA Archive

Then Extract IntelliJ Archive into /tmp
Possibly Double-Click on it in the File Manager.
Or from Command Line with:

tar xvzf ~/Downloads/idea*.tar.gz -C /tmp/

4. Relocate IntelliJ IDEA Contents

Next Relocate IntelliJ Idea Folder:

sudo su

If Got “User is Not in Sudoers file” then see: How to Enable sudo
Set up the root superUser as owner:

sudo chown -R root:root /tmp/idea*

And Switch the IntelliJ IDEA contents:

sudo mv /tmp/idea* /opt/idea

5. Making Symlink

Moreover, Make a Symlink into the working Path:

sudo ln -s /opt/idea/bin/idea.sh /usr/local/bin/idea.sh

6. Oracle Java Development Kit Installation

How to Install Required Oracle Java SE JDK for Ubuntu

7. Launching IntelliJ IDEA on Command Line

Starting IntelliJ IDEA from Shell:

idea.sh

8. IntelliJ IDEA Initial Setup

Follow with the Initial Customization Setup

First, choose the Theme for the UI:

Next Make a Desktop Launcher and Follow Up with the Wizard!

9. IntelliJ IDEA Getting-Started Guide

IntelliJ IDEA Getting-Started with Java Hello World