Java is a free, open-source programming language widely used in the distributed environment of the internet. There are two primary implementations: Oracle Java and OpenJDK. While Oracle Java includes some commercial features, OpenJDK is the open-source implementation of the Java Platform.
This tutorial will guide you through installing OpenJDK 8, OpenJDK 11, and Oracle Java 8 on CentOS 8.
Requirements
- A server running CentOS 8.
- Root privileges configured on your system.
Install OpenJDK 11
To begin, search for available OpenJDK versions in the CentOS 8 repository with the following command:
dnf search jdk
Expected output:
Last metadata expiration check: 1:23:41 ago on Wednesday 18 December 2019 02:23:23 AM EST. ========================================================= Summary & Name Matched: jdk ========================================================= java-11-openjdk-demo.x86_64 : OpenJDK Demos 11 java-1.8.0-openjdk-demo.x86_64 : OpenJDK Demos 8 java-11-openjdk-jmods.x86_64 : JMods for OpenJDK 11 java-11-openjdk-src.x86_64 : OpenJDK Source Bundle 11 java-1.8.0-openjdk-src.x86_64 : OpenJDK Source Bundle 8 java-11-openjdk.x86_64 : OpenJDK Runtime Environment 11 copy-jdk-configs.noarch : JDKs configuration files copier java-1.8.0-openjdk.x86_64 : OpenJDK Runtime Environment 8 java-11-openjdk-javadoc.x86_64 : OpenJDK 11 API documentation java-1.8.0-openjdk-javadoc.noarch : OpenJDK 8 API documentation java-11-openjdk-devel.x86_64 : OpenJDK Development Environment 11 java-1.8.0-openjdk-devel.x86_64 : OpenJDK Development Environment 8 java-11-openjdk-headless.x86_64 : OpenJDK Headless Runtime Environment 11 java-1.8.0-openjdk-accessibility.x86_64 : OpenJDK 8 accessibility connector java-1.8.0-openjdk-headless.x86_64 : OpenJDK Headless Runtime Environment 8 java-11-openjdk-javadoc-zip.x86_64 : OpenJDK 11 API documentation compressed in a single archive java-1.8.0-openjdk-javadoc-zip.noarch : OpenJDK 8 API documentation compressed in a single archive ============================================================ Summary Matched: jdk ============================================================= icedtea-web.noarch : Additional Java components for OpenJDK - Java browser plug-in and Web Start implementation
Install OpenJDK 11 by executing:
dnf install java-11-openjdk-devel.x86_64
Once the installation is complete, verify the installed Java version using:
java -version
The output should appear as follows:
openjdk version "11.0.5" 2019-10-15 LTS OpenJDK Runtime Environment 18.9 (build 11.0.5+10-LTS) OpenJDK 64-Bit Server VM 18.9 (build 11.0.5+10-LTS, mixed mode, sharing)
Install OpenJDK 8
Certain Java-based applications require OpenJDK 8. To install it, run the command:
dnf install java-1.8.0-openjdk-devel
Verify the installed version with:
java -version
Expected output:
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)
Switch Between Java Versions
You can simultaneously install multiple Java versions and switch among them as needed. Use the following command to switch from OpenJDK 8 to OpenJDK 11:
alternatives --config java
You’ll be prompted to choose your preferred Java version:
There are 2 programs which provide 'java'. Selection Command ----------------------------------------------- 1 java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.5.10-0.el8_0.x86_64/bin/java) *+ 2 java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.232.b09-0.el8_0.x86_64/jre/bin/java) Enter to keep the current selection[+], or type selection number: 1
Enter “1” and press Enter to switch to Java 11. Confirm your choice by checking the active Java version:
java -version
Install Oracle Java 8
You’ll need to log into the Oracle website and visit the Oracle Java 8 JDK Downloads Page. Accept the license agreement and download the jdk-8u231-linux-x64.rpm file.
Install Oracle Java 8 with:
dnf localinstall jdk-8u231-linux-x64.rpm
To verify the installation, run:
java -version
Expected outcome:
java version "1.8.0_231" Java(TM) SE Runtime Environment (build 1.8.0_231-b11) Java HotSpot(TM) 64-Bit Server VM (build 25.231-b11, mixed mode)
Conclusion
We have successfully installed different Java versions on CentOS 8. You’re now equipped to install your preferred Java version and switch between them as necessary.
FAQ
How can I check which version of Java is currently active?
You can check the active Java version by running the command java -version.
Can I have both OpenJDK 8 and OpenJDK 11 installed simultaneously?
Yes, you can have multiple versions installed and use the alternatives --config java command to switch between them.
Is OpenJDK free to use?
Yes, OpenJDK is open-source and free to use without commercial features.
Why would I choose Oracle Java over OpenJDK?
Oracle Java includes additional commercial features and support options that might be necessary for certain enterprise applications.