Java is a general purpose and object-oriented programming language. Java applications are compiled into Byte code and it only requires a Java Virtual Machine (JVM) to execute regardless of the computer architecture. That makes Java applications platform independent.
In this article, we are addressing; how to install Java runtime environment on CentOS 8.
Effective Java by Addison-Wesley Professional is a good book, if you want to start learning Java programming language.
Table of Contents:
- Environment Specification
- Installing OpenJDK Java Runtime Environment on CentOS 8
- Installing Oracle Java Runtime Environment on CentOS 8
- Using multiple Java Runtime Environments on same CentOS 8 server
Environment Specification:
We are using a virtual machine with minimally installed CentOS 8 server.
- CPU - 3.4 Ghz (2 cores)
- Memory - 2 GB
- Storage - 20 GB
- Operating System - CentOS 8
- Hostname – java-01.sysadminlabs.com
- IP Address - 192.168.116.206 /24
Installing OpenJDK Java Runtime Environment on CentOS 8:
OpenJDK is the free and open source implementation of Java Platform, Standard Edition (SE). OpenJDK is distributed under GNU GPL v2 license.
Two versions of OpenJDK are available in CentOS 8 standard yum repositories. i.e. OpenJDK 8 and OpenJDK 11. Obviously, they are the open source implementations of Oracle Java SE 8 and Oracle Java SE 11.
The installation steps are same for both versions. Here, we are installing OpenJDK 8 on our CentOS 8 server, but you can also install OpenJDK 11 by using the same steps.
Connect with java-01.sysadminlabs.com as root user by using a ssh tool and install OpenJDK java runtime environment.
[root@java-01 ~]# dnf install -y java-1.8.0-openjdk.x86_64
...
Upgraded:
lua-libs-5.3.4-11.el8.x86_64
Installed:
java-1.8.0-openjdk-1:1.8.0.232.b09-2.el8_1.x86_64
gtk2-2.24.32-4.el8.x86_64
alsa-lib-1.1.9-4.el8.x86_64
atk-2.28.1-1.el8.x86_64
cairo-1.15.12-3.el8.x86_64
copy-jdk-configs-3.7-1.el8.noarch
fribidi-1.0.4-7.el8_1.x86_64
gdk-pixbuf2-modules-2.36.12-5.el8.x86_64
giflib-5.1.4-3.el8.x86_64
graphite2-1.3.10-10.el8.x86_64
gtk-update-icon-cache-3.22.30-4.el8.x86_64
harfbuzz-1.7.5-3.el8.x86_64
hicolor-icon-theme-0.17-2.el8.noarch
jasper-libs-2.0.14-4.el8.x86_64
java-1.8.0-openjdk-headless-1:1.8.0.232.b09-2.el8_1.x86_64
javapackages-filesystem-5.3.0-1.module_el8.0.0+11+5b8c10bd.noarch
jbigkit-libs-2.1-14.el8.x86_64
libX11-1.6.7-1.el8.x86_64
libX11-common-1.6.7-1.el8.noarch
libXau-1.0.8-13.el8.x86_64
libXcomposite-0.4.4-14.el8.x86_64
libXcursor-1.1.15-3.el8.x86_64
libXdamage-1.1.4-14.el8.x86_64
libXext-1.3.3-9.el8.x86_64
libXfixes-5.0.3-7.el8.x86_64
libXft-2.3.2-10.el8.x86_64
libXi-1.7.9-7.el8.x86_64
libXinerama-1.1.4-1.el8.x86_64
libXrandr-1.5.1-7.el8.x86_64
libXrender-0.9.10-7.el8.x86_64
libXtst-1.2.3-7.el8.x86_64
libdatrie-0.2.9-7.el8.x86_64
libfontenc-1.1.3-8.el8.x86_64
libjpeg-turbo-1.5.3-10.el8.x86_64
libthai-0.1.27-2.el8.x86_64
libtiff-4.0.9-15.el8.x86_64
libxcb-1.13-5.el8.x86_64
lua-5.3.4-11.el8.x86_64
pango-1.42.4-6.el8.x86_64
pixman-0.36.0-1.el8.x86_64
ttmkfdir-3.0.9-54.el8.x86_64
tzdata-java-2019c-1.el8.noarch
xorg-x11-font-utils-1:7.5-40.el8.x86_64
xorg-x11-fonts-Type1-7.5-19.el8.noarch
avahi-libs-0.7-19.el8.x86_64
cups-libs-1:2.2.6-28.el8.x86_64
dejavu-fonts-common-2.35-6.el8.noarch
dejavu-sans-fonts-2.35-6.el8.noarch
fontconfig-2.13.1-3.el8.x86_64
fontpackages-filesystem-1.44-22.el8.noarch
gdk-pixbuf2-2.36.12-5.el8.x86_64
lksctp-tools-1.0.18-3.el8.x86_64
Complete!
We have installed OpenJDK Java Runtime Environment (JRE). Similarly, we can also install Java Development Kit (JDK) by installing package java-1.8.0-openjdk-devel.x86_64.
Define JAVA_PATH environment variable in /etc/profile file, so it can be set automatically while a login shell is initialized.
[root@java-01 ~]# echo "export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-2.el8_1.x86_64" >> /etc/profile
Also set the JAVA_PATH for the current shell.
[root@java-01 ~]# export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-2.el8_1.x86_64
Verify Java version.
[root@java-01 ~]# 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)
OpenJDK Java runtime environment has been installed on CentOS 8.
Installing Oracle Java Runtime Environment on CentOS 8:
Oracle Java is the proprietary distribution of Java platform. Oracle Java is available in Standard (SE), Enterprise (EE) and Micro Editions (ME).
Oracle Java SE is the default choice for most of the environments. Here, we are also installing the Oracle Java 13 SE on CentOS 8, that has been released recently.
Oracle Java SE 13 is available to download at Oracle website.
We are required an Oracle User Account for downloading Oracle Java SE 13. Therefore, login to Oracle website and download its RPM.
Transfer the downloaded file to java-01.sysadminlabs.com using WinSCP.
Connect to java-01.sysadminlabs.com as root user by using a ssh tool such as PuTTY.
Install Oracle Java SE 13 using dnf command.
[root@java-01 ~]# dnf install -y jdk-13.0.2_linux-x64_bin.rpm
Last metadata expiration check: 0:37:24 ago on Wed 22 Jan 2020 06:57:45 PM PKT.
Dependencies resolved.
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
jdk-13.0.2 x86_64 2000:13.0.2-ga @commandline 163 M
Transaction Summary
================================================================================
Install 1 Package
Total size: 163 M
Installed size: 308 M
Downloading Packages:
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : jdk-13.0.2-2000:13.0.2-ga.x86_64 1/1
Running scriptlet: jdk-13.0.2-2000:13.0.2-ga.x86_64 1/1
Verifying : jdk-13.0.2-2000:13.0.2-ga.x86_64 1/1
Installed:
jdk-13.0.2-2000:13.0.2-ga.x86_64
Complete!
Define JAVA_PATH environment variable in /etc/profile file, so it can be set automatically while a login shell is initialized.
[root@java-01 ~]# echo "export JAVA_HOME=/usr/java/jdk-13.0.2" >> /etc/profile
Also set the JAVA_PATH for the current shell.
[root@java-01 ~]# export JAVA_HOME=/usr/java/jdk-13.0.2
Verify Java version.
[root@java-01 ~]# java -version
java version "13.0.2" 2020-01-14
Java(TM) SE Runtime Environment (build 13.0.2+8)
Java HotSpot(TM) 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)
We have successfully installed Oracle Java SE 13 on our CentOS 8 server.
Using multiple Java Runtime Environments on same CentOS 8 server:
We have installed OpenJDK Java 8 and Oracle Java SE 13 on the same CentOS 8 server.
Both of these Java versions are available on the server, but only one is set as default java runtime environment.
Since, we have installed Oracle Java SE 13 over OpenJDK 8. Therefore, we are now running the Oracle Java SE 13 as default java runtime environment.
To switch to OpenJDK 8, we can use the alternatives command.
[root@java-01 ~]# alternatives --config java
There are 2 programs which provide 'java'.
Selection Command
-----------------------------------------------
1 java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-2.el8_1.x86_64/jre/bin/java)
*+ 2 /usr/java/jdk-13.0.2/bin/java
Enter to keep the current selection[+], or type selection number: 1
We have set the OpenJDK 8 as default Java runtime environment.
Verify the version of Java now.
[root@java-01 ~]# 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)
You can see that, OpenJDK 8 has been set as our default Java runtime environment.
Installation of Java runtime environment on CentOS 8 has been completed.
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