Unclear instructions on how to add Java_Home to Linux startup script

[jimothyclark]

I am VERY new to all of this, but I am humble enough to admit that I am a novice and I am coachable enough to learn from anyone! I have researched a couple best practices to avoid stepping on anyone's toes, but I am happy to learn ways my use of this site could improve.

I am learning Linux and I am trying to do configure Java_Home on my Linux. So far, I have barely done more than install a few virtual machines (CentOS 7 and two clones; CentOS7 Full DVD and CentOS 7 NetInstall).
My Jenkins course on stackskills.com referred me to GitHub with my questions and I'm having trouble with the following instructions on how to add Java_Home to my startup script:

Configure Java_Home on Linux:
Login to your account and open the startup script file which is usually ~/.bash_profile file (or can be .bashrc depending on your envrionment settings)
$ vi ~/.bash_profile

In the startup script, set JAVA_HOME and PATH

C shell:

setenv JAVA_HOME jdk-install-dir
setenv PATH $JAVA_HOME/bin:$PATH
export PATH=$JAVA_HOME/bin:$PATH
jdk-install-dir is the JDK installation director, which should be something similar to /usr/java/jdk1.5.0_07/bin/java

Bourne shell:

JAVA_HOME=jdk-install-dir
export JAVA_HOME
PATH=$JAVA_HOME/bin:$PATH
export PATH
Korn and bash shells:

export JAVA_HOME=jdk-install-dir
export PATH=$JAVA_HOME/bin:$PATH
Type the following command to activate the new path settings immediately:

$ source ~/.bash_profile

Verify new settings:

$ echo $JAVA_HOME

$ echo $PATH

I'm not exactly sure how to use these instructions. Below is a screenshot of my VM and, from the formatting, it looks like I have the Bourne shell.

Please advise...

[Vishal31122000]

Also you can use this if running on ubuntu and setting up the directory for maven. (check your respective version of jdk)

~/.profile: executed by Bourne-compatible login shells.

if [ "$BASH" ]; then
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
fi

Set JAVA_HOME to the desired Java installation directory

JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64

Append Java bin directory to PATH

PATH=$PATH:$JAVA_HOME/bin

export PATH JAVA_HOME
M2_HOME=/usr/share/maven
M2=$M2_HOME/bin
PATH=$PATH:$M2_HOME:$M2

mesg n 2> /dev/null || true