# Install JAVA

By

Charl Cronje

Install the Java Development Kit with the following command:

sudo yum install java-11-openjdk-devel

Install OpenJRE 11

Java Runtime Environment 11 (Open JRE 11) is a subset of OpenJDK. Therefore, both packages are included in the command:

sudo yum install java-11-openjdk

The official Oracle JDK is not available for download from the local repository. You have to download the .rpm package from the Java SE Downloads page.

After the download is complete, you can install the package with the command:

sudo yum localinstall jre-VERSION-linux-x64.rpm

The following command shows which Java release you have and confirms installation was successful:

java –version

You can also install any of the other versions of Java by changing the version number in the command.

• You may decide to use Open JDK 8, instead of the default OpenJDK 11.
• To do so, type in the following command in the terminal:

sudo yum install java-1.8.0-openjdk-devel

As a subset of Open JDK 8, you can install Open JRE 8 by typing in the command:

sudo yum install java-1.8.0-openjdk

• As previously mentioned, you have to download Oracle Java from its official page.
• To install the newest version, simply download the appropriate package from their webpage and continue with the installation.

• Since you can have multiple versions of Java installed on your system, you can decide which one is the default one. To do so;
• Run a command that shows all the installed versions on your computer:

sudo alternatives --config java

• The image above shows that there are two alternatives to this system. These choices are represented by numbers 1 (Java 11) and 2 (Java 8).
• To change the default version, type the associated number (in this case, 1 or 2) and press Enter.

1. First, locate where Java is installed:

sudo update-alternatives --config java

In the output, you can find the path for each Java package installed on the system.

• /usr/lib/jvm/java-11-openjdk-11.0.3.7-0.el7_6.x86_64/bin/java (where OpenJDK 11 is located)
• /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.212.b04-0.el7_6.x86_64/jre/bin/java (where OpenJDK 8 is located)

2. Once you see all the paths, copy the one of your preferred Java version.
3. Then, open the .bash_profile with any text editor. In this example, we use vim:

nano .bash_profile

4. At the bottom of the file, add a line which specifies the location of JAVA_HOME and JAVA_JRE in the following manner:

You will get the following output.

export JAVA_HOME="/your/installation/path/"
export JRE_HOME="/your/installation/path/jre"

For example, if we copy the installation path for Java 11 in the previous step, the added line in the text editor will be:

/usr/lib/jvm/java-11-openjdk-11.0.3.7-0.el7_6.x86_64/bin/java

Now source the file using the following command.

source ~/.bash_profile

Now you can run the echo $JAVA_HOME and echo $JAVA_JRE command again to check if the environment variable is set or not.