How to install Oracle jdk8 on ubuntu 18.04

Step 1: Download Oracle Java 8

https://www.oracle.com/technetwork/java/javase/downloads/java-archive-javase8-2177648.html

Step 2: Copy downloaded Setup and Extract

Create a directory:

sudo mkdir  -p /opt/jdk

Copy the tar file from the directory copied from local machine to server to /opt/jdk folder and execute below command:

sudo cp -rf /home/afikur/jdk-8u202-linux-x64.tar.gz /opt/jdk/

cd /opt/jdk/

sudo tar -zxf jdk-8u202-linux-x64.tar.gz

Now unarchived the file and check the content by long-list:

ls

Step 3: Install Oracle Java 8 on ubuntu with Alternatives

Use update-alternatives command to configure java on your system

sudo update-alternatives --install /usr/bin/java java /opt/jdk/jdk1.8.0_202/bin/java 100

After executing above command it shows below output:

Output:

update-alternatives: using /opt/jdk/jdk1.8.0_202/bin/java to provide /usr/bin/java (java) in auto mode

Step 4: Verify Update Alternatives

sudo update-alternatives --display java

Output:

java - auto mode
link best version is /opt/jdk/jdk1.8.0_202/bin/java
link currently points to /opt/jdk/jdk1.8.0_202/bin/java
link java is /usr/bin/java
/opt/jdk/jdk1.8.0_202/bin/java - priority 100
/opt/jdk/jdk1.8.0_202/bin/javac - priority 100

To change for alternative mode:

sudo update-alternatives --config java

It prompts for selecting by 0,1,2..so choose accordingly: Output

There are 2 choices for the alternative java (providing /usr/bin/java).

Selection Path Priority Status

• 0 /opt/jdk/jdk1.8.0_202/bin/java 100 auto mode

  1 /opt/jdk/jdk1.8.0_231/bin/java 100 manual mode

  2 /opt/jdk/jdk1.8.0_202/bin/javac 100 manual mode

Press to keep the current choice[*], or type selection number:

Step 5: Setting the JAVA_HOME and JRE_HOME Environment Variables

To define the enviroment variable:

sudo  nano /etc/environment

Paste the below varible on the file:

JAVA_HOME=/opt/jdk/jdk1.8.0_202
JRE_HOME=/opt/jdk/jdk1.8.0_202/jre

To check variables defined:

source /etc/environment

echo $JAVA_HOME

Output:

/opt/jdk/jdk1.8.0_202

sudo apt-get update

Step 6: Verify Java Version

To check the java version:

java -version

Output:

java version "1.8.0_202"
Java(TM) SE Runtime Environment (build 1.8.0_202-b08)
Java HotSpot(TM) 64-Bit Server VM (build 25.202-b08, mixed mode)

If you seeing output like above then we have successfully set up the Java 8 on Ubuntu.

Conclusion

In this article, We have downloaded Oracle Java 8 from official site, installed using command line, configured JAVA_HOME and JRE_HOME, verified installed version.