Installing Multiple JVMs on a Mac Manually and Switching Manually with latest Default

This blog will show you now to install multiple version of java manually on a Mac, and switch between them manually.  It will also show how to set and maintain the default java to the "latest" version.

First, Check if there are any version of java installed.  I just bought a 2013 iMac on Ebay, and set it up tabula rosa.

iMac:~ $ /usr/libexec/java_home -V

Unable to find any JVMs matching version "(null)".

Matching Java Virtual Machines (0):

Default Java Virtual Machines (0):

No Java runtime present, try --request to install.

Mac OS looks for java in the /Library/Java/JavaVirtualMachines/ directory.  Therefore if we download a valid Java JDK, and "copy" the un-archived structure over to that directory, we will see that it works.  This is done as follows.

Java 13 is available from Java 13 link - > https://jdk.java.net/13/ or it can obtained via wget with:

iMac:java $ wget https://download.java.net/java/GA/jdk13.0.2/d4173c853231432d94f001e99d882ca7/8/GPL/openjdk-13.0.2_osx-x64_bin.tar.gz

--2020-02-04 19:01:16--  https://download.java.net/java/GA/jdk13.0.2/d4173c853231432d94f001e99d882ca7/8/GPL/openjdk-13.0.2_osx-x64_bin.tar.gz

Resolving download.java.net (download.java.net)... 104.87.12.11

Connecting to download.java.net (download.java.net)|104.87.12.11|:443... connected.

HTTP request sent, awaiting response... 200 OK

Length: 189969691 (181M) [application/x-gzip]

Saving to: ‘openjdk-13.0.2_osx-x64_bin.tar.gz’

openjdk-13.0.2_osx-x64_bin.tar.gz        7%[====>    ]  13.50M   254KB/s    eta 9m 8s  

Once this has been downloaded:  it can be extracted and copied or move to the /Library/Java/JavaVirtualMachines/ directory.

Extract with the "tar -xvzf openjdk-13.0.2_osx-x64_bin.tar.gz" which says eXtract Verbose Compressed(z) Filesystem.

$ tar -xvzf openjdk-13.0.2_osx-x64_bin.tar.gz
$ mv jdk-13.0.1.jdk/ /Library/Java/JavaVirtualMachines/

Re-running the /usr/libexec/java_home -V command gives:

$ /usr/libexec/java_home -V

Matching Java Virtual Machines (1):

    13.0.1, x86_64: "OpenJDK 13.0.1" /Library/Java/JavaVirtualMachines/jdk-13.0.1.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/jdk-13.0.1.jdk/Contents/Home

And 'java -version' on the command line gives:

$ java -version

openjdk version "13.0.1" 2019-10-15

OpenJDK Runtime Environment (build 13.0.1+9)

OpenJDK 64-Bit Server VM (build 13.0.1+9, mixed mode, sharing)

After downloading and installing several different version of java (which included creating an oracle account, and getting one of the "legacy/archived" version of java from the oracle website) my lib execute for java home looked like this:

$ /usr/libexec/java_home -V

Matching Java Virtual Machines (4):

    13.0.1, x86_64: "OpenJDK 13.0.1" /Library/Java/JavaVirtualMachines/jdk-13.0.1.jdk/Contents/Home

    11.0.6, x86_64: "Java SE 11.0.6" /Library/Java/JavaVirtualMachines/jdk-11.0.6.jdk/Contents/Home

    1.8.0_241, x86_64: "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_241.jdk/Contents/Home

    1.7.0_80, x86_64: "Java SE 7" /Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/jdk-13.0.1.jdk/Contents/Home

Now it might make sense to just add some convenience methods to the environment files.  Basically this is the step to make it very easy to switch to different version of java on the command line:

PLACE THIS IN YOUR ~/.bash_profile or other startup environment script directory

export  JAVA_HOME_7=$(/usr/libexec/java_home -v1.7)

export  JAVA_HOME_8=$(/usr/libexec/java_home -v1.8)

#export JAVA_HOME_9=$(/usr/libexec/java_home -v9)

#export JAVA_HOME_10=$(/usr/libexec/java_home -v10)

export  JAVA_HOME_11=$(/usr/libexec/java_home -v11)

export  JAVA_HOME_13=$(/usr/libexec/java_home -v13)

alias java7='export JAVA_HOME=$JAVA_HOME_7'

alias java8='export JAVA_HOME=$JAVA_HOME_8'

#alias java9='export JAVA_HOME=$JAVA_HOME_9'

#alias java10='export JAVA_HOME=$JAVA_HOME_10'

alias java11='export JAVA_HOME=$JAVA_HOME_11'

#alias java12='export JAVA_HOME=$JAVA_HOME_12'

alias java13='export JAVA_HOME=$JAVA_HOME_13'

#default

java13

Source your newly modified .bash_profile (this only needs to be done once, and not after a login logout...)
$ source ~/.bash_profile
Now switching from java13 to java7 is as easy as typing $ java7 at the command line E.G.

iMac:~ $ java7

iMac:~ $ java -version

java version "1.7.0_80"

Java(TM) SE Runtime Environment (build 1.7.0_80-b15)

Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)

iMac:~ $ java8

iMac:~ $ java -version

java version "1.8.0_241"

Java(TM) SE Runtime Environment (build 1.8.0_241-b07)

Java HotSpot(TM) 64-Bit Server VM (build 25.241-b07, mixed mode)

iMac:~ $ java11

iMac:~ $ java -version

java version "11.0.6" 2020-01-14 LTS

Java(TM) SE Runtime Environment 18.9 (build 11.0.6+8-LTS)

Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.6+8-LTS, mixed mode)

iMac:~ $ java13

iMac:~ $ java -version

openjdk version "13.0.1" 2019-10-15

OpenJDK Runtime Environment (build 13.0.1+9)

OpenJDK 64-Bit Server VM (build 13.0.1+9, mixed mode, sharing)