Can multiple major versions of java be installed on Red Hat Enterprise Linux?

Environment

• Red Hat Enterprise Linux

Issue

• Can I install multiple java major versions on Red Hat Enterprise Linux systems?
• I want to install java-1.8.0-openjdk.x86_64 and java-11-openjdk.x86_64 packages on RHEL, is it possible?
• If I install multiple versions of java i.e. java-1.8.0-openjdk.x86_64 and java-11-openjdk.x86_64 on RHEL, which would be taken as default?

Resolution

• Yes. Installing multiple java major version packages is possible.

  • Below is an example from the system after installing 1.8.0, 11 and 17 versions of OpenJDK(java-1.8.0-openjdk.x86_64, java-11-openjdk.x86_64 and java-17-openjdk.x86_64)

  # alternatives --config java
   
  There are 3 programs which provide 'java'.
  
  Selection    Command
  -----------------------------------------------
  1           java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.322.b06-9.el9.x86_64/jre/bin/java)
  2           java-17-openjdk.x86_64 (/usr/lib/jvm/java-17-openjdk-17.0.2.0.8-5.el9.x86_64/bin/java)
  *+ 3           java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.14.1.1-6.el9.x86_64/bin/java)
  
  Enter to keep the current selection[+], or type selection number:
  

• The default system java (+) would be set to the java package having the highest priority value.

  # java -version
  openjdk version "11.0.14.1" 2022-02-08 LTS
  OpenJDK Runtime Environment 18.9 (build 11.0.14.1+1-LTS)
  OpenJDK 64-Bit Server VM 18.9 (build 11.0.14.1+1-LTS, mixed mode, sharing)
  
  # alternatives --display java | grep -i priority
  /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.322.b06-9.el9.x86_64/jre/bin/java - family java-1.8.0-openjdk.x86_64 priority 1
  /usr/lib/jvm/java-17-openjdk-17.0.2.0.8-5.el9.x86_64/bin/java - family java-17-openjdk.x86_64 priority 1
  /usr/lib/jvm/java-11-openjdk-11.0.14.1.1-6.el9.x86_64/bin/java - family java-11-openjdk.x86_64 priority 11001421
  

• It can be configured to another version by providing the selection in the above alternatives --config java command.

Diagnostic Steps

If you wish to install multiple copies of the same minor version of Java, refer to:

• How to install multiple minor versions of OpenJDK on a Red Hat Enterprise Linux system?

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