I got an assist and was able to install what I wanted. I did:

[ec2-user@ip-172-31-9-107 nifi]$ yum search java | grep "1.8"
Last metadata expiration check: 1:00:33 ago on Tue Aug  8 18:28:56 2023.
java-1.8.0-amazon-corretto.x86_64 : Amazon Corretto runtime environment
java-1.8.0-amazon-corretto-devel.x86_64 : Amazon Corretto development environment

,and then:

sudo yum install java-1.8.0-amazon-corretto.x86_64 

which installed:

[ec2-user@ip-172-31-9-107 nifi]$ java -version
openjdk version "1.8.0_382"

The Repository needed to be enable first before open JDK 8 could be installed.

sudo yum update
sudo yum repolist all

Check the repo id ultra-centos-7.x-openjdk exists.

sudo yum-config-manager --enable ultra-centos-7.x-openjdk
sudo yum install java-1.8.0-openjdk-devel

Confirm the installation using -

java -version

yum search jdk

Results:

java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment
java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment

So you could likely run:

yum install java-1.8.0-openjdk.x86_64 java-1.8.0-openjdk-devel.x86_64

If that doesn't work, try a yum clean all and repeat.

Edit: You could also search the FTP repo link you posted...

The JDK should be installed after installing this package, you can check with:

sudo alternatives --config javac

The JRE is just installed inside the /jre subdirectory.

java-1.8.0-openjdk-devel and java-1.8.0-openjdk versions need to match exactly.

in short:

yum downgrade java-1.8.0-openjdk-1.8.0.161-2.b14.el7
yum install java-1.8.0-openjdk-devel-1.8.0.161-2.b14.el7.x86_64.rpm

I just wrote a whole answer to this question here: https://stackoverflow.com/questions/57498755/installing-python36-devel-on-rhel7-failing/57519956#57519956

The following command will return a list of all packages directly related to Java. They will be in the format of java-<version>.

$ yum search java | grep 'java-'

If there are no available packages, then you may need to download a new repository to search through. I suggest taking a look at Dag Wieers' repo. After downloading it, try the above command again.

You will see at least one version of Java packages available for download. Depending on when you read this, the lastest available version may be different.

java-1.7.0-openjdk.x86_64

The above package alone will only install JRE. To also install javac and JDK, the following command will do the trick:

$ yum install java-1.7.0-openjdk*

These packages will be installing (as well as their dependencies):

java-1.7.0-openjdk.x86_64
java-1.7.0-openjdk-accessibility.x86_64
java-1.7.0-openjdk-demo.x86_64
java-1.7.0-openjdk-devel.x86_64
java-1.7.0-openjdk-headless.x86_64
java-1.7.0-openjdk-javadoc.noarch
java-1.7.0-openjdk-src.x86_64

Below are steps to find the java:

find / -name java | grep "/bin/java" ---> This will give all paths where you have executable of java

[root@XXXXX ~]# find / -name java | grep "/bin/java"
/usr/bin/java
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-1.el6_10.x86_64/bin/java
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-1.el6_10.x86_64/jre/bin/java

Once you find the locations just make the below entry for java home for machine: vi /etc/profile ---> add the below lines to the end

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-1.el6_10.x86_64
export PATH=$JAVA_HOME/bin:$PATH

[root@XXXXX ~]# java -version
openjdk version "1.8.0_232"
OpenJDK Runtime Environment (build 1.8.0_232-b09)
OpenJDK 64-Bit Server VM (build 25.232-b09, mixed mode)

In your example you are giving path for JDK not for OpenJDk as below: export JAVA_HOME=/usr/jdk/jdk1.8.0_121 export PATH=$JAVA_HOME/bin:$PATH

Thats why it is showing java even though you have installed OpenJDK.

Let me know if you have any queries.