When Eclipse is started in Ubuntu, the following error occurs: A Java RunTime Environment (JRE) or Java Development Kit (JDK) must, ubuntueclipse

When Eclipse is started in Ubuntu, the following error occurs: A Java RunTime Environment (JRE) or Java Development Kit (JDK) must, ubuntueclipse

I thought it was jdk's environment variable configuration error. So I found a variety of methods to configure the environment variables from the Internet and paid attention to the space issue. No matter how I changed it, I still reported this error! Later, I saw a strange method on the Internet. I don't know why it's okay?

Method: enter your eclipse directory, open it on the terminal, switch to root, and enter:
Mkdir jre
Cd jre
Ln-s your JDK directory/bin

If you know why you want to post it, thank you.