Manage multiple java versions on macOS using brew and jenv

Install and Update on macOS

Manage multiple java versions on macOS can be tricky. There's different ways to install:

homebrew cask
download java distribution from Oracle
download java distribution from java.com

And once the java version becomes outdated, there's different ways to upgrade too, which we will discuss below.

Upgrade from `brew cask`

homebrew cask doesn't offer the ability to upgrade a package, as brew cask upgrade <pkg-name> is not even available, see [details](https://github.com/caskroom/homebrew-cask/issues/4678). The closest alternative is homebrew cask reinstall <pkg-name>

Upgrade from "Java Preference Panel"

Be cautions about this approach as it may leave you multiple java versions in multiple places.

Why? A jdk for macOS comes in two component:

'Java Preference Panel' give us the path:

/Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home
/usr/libexec/java_home -V gives us:

/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home

A homebrew cask install will download the latest package at /usr/local/Caskroom/java/, then install to both directories, whereas if you install the package you downloaded from java.com, or upgrade the package from 'Java Preference Panel', it only installs/upgrades the Web Applet plugin.

There's also /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/ folder, which maintains a copy of bin commands in current java installation, and it will be updated when a new version of jdk is installed.

Below is from one of the answers to question: [How to properly upgrade Java](https://discussions.apple.com/thread/7630285?start=0&tstart=0)

>When you download Java from Oracle, it only installs the Web Applet Plugin. If you installed the Java 1.8 JDK previously, >then later installed the applet plugin, they could be at two different versions.

In essence, there are two parts to Java on OS X. There is a web plugin(JRE) and a JDk. They are entirely separate components. The direct download at Java.com will only install the web plugin(JRE). The JDK download will install both the JVM and the web plugin.

The following is the output of uninstall java:

➜  ~ brew cask uninstall java
==> Uninstalling Cask java
==> Running uninstall process for java; your password may be necessary
==> Removing launchctl service com.oracle.java.Helper-Tool
==> Removing launchctl service com.oracle.java.Java-Updater
==> Quitting application ID com.oracle.java.Java-Updater
==> Quitting application ID net.java.openjdk.cmd
==> Uninstalling packages:
com.oracle.jdk8u131
com.oracle.jre
==> Removing files:
/Library/Internet Plug-Ins/JavaAppletPlugin.plugin
/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents
/Library/PreferencePanes/JavaControlPanel.prefPane
/Library/Java/Home
==> Purging files for version 1.8.0_131-b11,d54c1d3a095b4ff2b6607d096fa80163 of Cask java

This shows a brew cask uninstall uninstalls both jdk and jre.

Then I installed latest java8 using brew cask install java8~(~brew tap caskroom/versions first). Then all 3 locations show the latest version:

/Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java -version
/Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home/bin/javac -version
/System/Library/Frameworks/JavaVM.framework/Versions/A/Commands/javac -version

Install and maintain multiple java versions including java 7

Install another version of java(java 7) from Oracle

Why not use brew cask you may ask, see https://github.com/caskroom/homebrew-cask/issues/37772 for details.

It is fairly easy to install java 7 from Oracle though:

manually download java 7. Reason:
manually install the dmg file.

My observation is that when existing java is already installed, trying to install a different version with dmg file from Oracle is pretty non-destructive:

There is one more entry is added

➜  ~ /usr/libexec/java_home -V
Matching Java Virtual Machines (2):
    1.8.0_152, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home
    1.7.0_80, x86_64:	"Java SE 7"	/Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home

But other than that, nothing is changed

~ java -version
java version "1.8.0_152"

➜  ~ echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home

In particular, /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/ is not updated to the new version.

Install jenv to manage multiple java version

First, we need to install jenv

➜  ~ brew update
➜  ~ brew install jenv
/usr/local/Cellar/jenv/0.4.4: 78 files, 66KB, built in 1 second
➜  ~ which jenv
/usr/local/bin/jenv
➜  ~ jenv --version
jenv 0.4.4

➜  ~ echo 'export PATH="$HOME/.jenv/bin:$PATH"' >> ~/.zshrc
➜  ~ echo 'eval "$(jenv init -)"' >> ~/.zshrc

Next we need to configure jenv to manage multiple java version. We add them into jenv:

➜  ~ jenv add /Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home
or with ~java_home~ command:
➜  ~ jenv add $(/usr/libexec/java_home -v 1.8)
oracle64-1.8.0.152 added
1.8.0.152 added
1.8 added
➜  ~ jenv add /Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home
or with ~java_home~ command:
➜  ~ jenv add $(/usr/libexec/java_home -v 1.7)
oracle64-1.7.0.80 added
1.7.0.80 added
1.7 added

Then set one as global:

➜  ~ jenv global 1.8
➜  ~ jenv enable-plugin export
You may restart your session to activate jenv export plugin echo export plugin activated

Finally, after restarting manually, we verify that $JAVA_HOME has been exported by jenv correctly

➜  ~ echo $JAVA_HOME
/Users/lzhou/.jenv/versions/1.8

➜  ~ $JAVA_HOME/bin/java -version
java version "1.8.0_152"
Java(TM) SE Runtime Environment (build 1.8.0_152-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)

Install java 10

As the time of writing, brew cask install java installs java 10.

Install:


➜  lzhoucs.github.io git:(master) brew cask install java
Updating Homebrew...
==> Auto-updated Homebrew!
==> Caveats
This Cask makes minor modifications to the JRE to prevent issues with
packaged applications, as discussed here:

  https://bugs.eclipse.org/bugs/show_bug.cgi?id=411361

If your Java application still asks for JRE installation, you might need
to reboot or logout/login.

Installing this Cask means you have AGREED to the Oracle Binary Code
License Agreement for Java SE at

  https://www.oracle.com/technetwork/java/javase/terms/license/index.html

==> Satisfying dependencies
==> Downloading http://download.oracle.com/otn-pub/java/jdk/10.0.1+10/fb4372174a714e6b8c52526dc134031e/jdk-10.0.1_osx-x64_bin.dmg
######################################################################## 100.0%j
==> Verifying checksum for Cask java
==> Installing Cask java
==> Running installer for java; your password may be necessary.
==> Package installers may write to any location; options such as --appdir are ignored.
==> installer: Package name is JDK 10.0.1
==> installer: Upgrading at base path /
==> installer: The upgrade was successful.
🍺  java was successfully installed!

Verify nothing has changed except for a new entry is added into java_home

➜  lzhoucs.github.io git:(master) ✗ java -version
java version "1.8.0_152"
Java(TM) SE Runtime Environment (build 1.8.0_152-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)

➜  lzhoucs.github.io git:(master) ✗ /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java -version
java version "1.8.0_152"
Java(TM) SE Runtime Environment (build 1.8.0_152-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.152-b16, mixed mode)

➜  lzhoucs.github.io git:(master) ✗ echo $JAVA_HOME
/Users/lzhou/.jenv/versions/1.8

➜  lzhoucs.github.io git:(master) ✗ /usr/libexec/java_home -V
Matching Java Virtual Machines (3):
    10.0.1, x86_64:	"Java SE 10.0.1"	/Library/Java/JavaVirtualMachines/jdk-10.0.1.jdk/Contents/Home
    1.8.0_152, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_152.jdk/Contents/Home
    1.7.0_80, x86_64:	"Java SE 7"	/Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home

Add java 10 into jenv

➜  lzhoucs.github.io git:(master) ✗ jenv add $(/usr/libexec/java_home -v 10)
oracle64-10.0.1 added
10.0.1 added
10.0 added

List current versions in jenv

➜  lzhoucs.github.io git:(master) ✗ jenv versions
  system
  1.7
  1.7.0.80
* 1.8 (set by /Users/lzhou/.jenv/version)
  1.8.0.152
  10.0
  10.0.1
  oracle64-1.7.0.80
  oracle64-1.8.0.152
  oracle64-10.0.1

So exactly what does jenv global <java-version> do behind the scene? It does the following:

It sets the new <java-version> in ~/.jenv/version file which current java in the Path is reading from
It updates $JAVA_HOME(requires restart terminal to take effect)
It updates /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/ to point to new java version(my observation)

Java macOS