How to set or change the default Java (JDK) version on macOS? [duplicate]

Question

How can you change the default version of Java on a mac?

Answer 1

First run /usr/libexec/java_home -V which will output something like the following:

Matching Java Virtual Machines (3):
1.8.0_05, x86_64:   "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home
1.6.0_65-b14-462, x86_64:   "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
1.6.0_65-b14-462, i386: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/jdk1.8.0_05.jdk/Contents/Home

Pick the version you want to be the default (1.6.0_65-b14-462 for arguments sake) then:

export JAVA_HOME=`/usr/libexec/java_home -v 1.6.0_65-b14-462`

or you can specify just the major version, like:

export JAVA_HOME=`/usr/libexec/java_home -v 1.8`

Now when you run java -version you will see:

java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)

Add the export JAVA_HOME… line to your shell’s init file.

For Bash (as stated by antonyh):

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)

For Fish (as stated by ormurin)

set -x JAVA_HOME (/usr/libexec/java_home -d64 -v1.8)

Updating the .zshrc file should work:

nano ~/.zshrc

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8.0)

Press CTRL+X to exit the editor Press Y to save your changes

source ~/.zshrc
echo $JAVA_HOME
java -version

Answer 2

This answer is an attempt to address: how to control java version system-wide (not just in currently running shell) when several versions of JDK are installed for development purposes on macOS El Capitan or newer (Sierra, High Sierra, Mojave). As far as I can tell, none of the current answers do that (*).

As a developer, I use several JDKs, and I want to switch from one to the other easily. Usually I have the latest stable one for general use, and others for tests. But I don't want the system (e.g. when I start my IDE) to use the latest "early access" version I have for now. I want to control system's default, and that should be latest stable.

The following approach works with Java 7 to 12 at least (early access at the time of this writing), with Oracle JDK or OpenJDK (including builds by AdoptOpenJDK produced after mid-October 2018).

Solution without 3rd party tools:

• leave all JDKs at their default location, under /Library/Java/JavaVirtualMachines. The system will pick the highest version by default.
• To exclude a JDK from being picked by default, rename its Contents/Info.plist to Info.plist.disabled. That JDK can still be used when $JAVA_HOME points to it, or explicitly referenced in a script or configuration. It will simply be ignored by system's java command.

System launcher will use the JDK with highest version among those that have an Info.plist file.

When working in a shell with alternate JDK, pick your method among existing answers (jenv, or custom aliases/scripts around /usr/libexec/java_home, etc).

---

Details of investigation in this gist.

---

(*) Current answers are either obsolete (no longer valid for macOS El Capitan or Sierra), or only address a single JDK, or do not address the system-wide aspect. Many explain how to change $JAVA_HOME, but this only affects the current shell and what is launched from there. It won't affect an application started from OS launcher (unless you change the right file and logout/login, which is tedious). Same for jenv, it's cool and all, but as far as I can tell it merely changes environment variables, so it has the same limitation.

Answer 3

Adding to the above answers, I put the following lines in my .bash_profile (or .zshrc for MacOS 10.15+) which makes it really convenient to switch (including @elektromin's comment for java 9):

alias j20="export JAVA_HOME=`/usr/libexec/java_home -v 20`; java -version"
alias j19="export JAVA_HOME=`/usr/libexec/java_home -v 19`; java -version"
alias j18="export JAVA_HOME=`/usr/libexec/java_home -v 18`; java -version"
alias j17="export JAVA_HOME=`/usr/libexec/java_home -v 17`; java -version"
alias j16="export JAVA_HOME=`/usr/libexec/java_home -v 16`; java -version"
alias j15="export JAVA_HOME=`/usr/libexec/java_home -v 15`; java -version"
alias j14="export JAVA_HOME=`/usr/libexec/java_home -v 14`; java -version"
alias j13="export JAVA_HOME=`/usr/libexec/java_home -v 13`; java -version"
alias j12="export JAVA_HOME=`/usr/libexec/java_home -v 12`; java -version"
alias j11="export JAVA_HOME=`/usr/libexec/java_home -v 11`; java -version"
alias j10="export JAVA_HOME=`/usr/libexec/java_home -v 10`; java -version"
alias j9="export JAVA_HOME=`/usr/libexec/java_home -v 9`; java -version"
alias j8="export JAVA_HOME=`/usr/libexec/java_home -v 1.8`; java -version"
alias j7="export JAVA_HOME=`/usr/libexec/java_home -v 1.7`; java -version"

After inserting, execute $ source .bash_profile

I can switch to Java 8 by typing the following:

$ j8
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)

Answer 4

Due to multiple Homebrew, cast(Deprecation Notice AdoptOpenJDK/openjdk), and MacOS updates I'm posting this updated answer.

Homebrew tap AdoptOpenJDK/openjdk is officially deprecated in favor of the temurin casks provided directly from the Homebrew project but Homebrew is the best way to manage and work with different Java versions.

In case you already have Homebrew and AdoptOpenJDK/openjdk cast installed, please untap this brew tap first:

$ brew untap AdoptOpenJDK/openjdk

if you do not have Homebrew installed.

1 - Install Homebrew.

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

2 - To Install the latest Java version with temurin:

$ brew install --cask temurin

3 - To install other versions:

$ brew tap homebrew/cask-versions
$ brew install --cask temurin@8
$ brew install --cask temurin@11
$ brew install --cask temurin@17
$ brew install --cask temurin@18
$ brew install --cask temurin@19
$ brew install --cask temurin@21

4 - Switch between different versions of Java

Switching between different versions of Java, you only need to add the following to your .bash_profile or .zshrc.

In this case, we want to be able to switch between Java8, Java11, Java17... and Java21:

export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)
export JAVA_11_HOME=$(/usr/libexec/java_home -v11)
export JAVA_17_HOME=$(/usr/libexec/java_home -v17)
export JAVA_18_HOME=$(/usr/libexec/java_home -v18)
export JAVA_19_HOME=$(/usr/libexec/java_home -v19)
export JAVA_21_HOME=$(/usr/libexec/java_home -v21)

alias java8='export JAVA_HOME=$JAVA_8_HOME'
alias java11='export JAVA_HOME=$JAVA_11_HOME'
alias java17='export JAVA_HOME=$JAVA_17_HOME'
alias java18='export JAVA_HOME=$JAVA_18_HOME'
alias java19='export JAVA_HOME=$JAVA_19_HOME'
alias java21='export JAVA_HOME=$JAVA_21_HOME'

# default to Java 21
java21

5 - Reload .bash_profile or .zshrc for the aliases to take effect:

$ source ~/.bash_profile

or

$ source ~/.zshrc

6 - Finally you can use the aliases to switch between different Java versions.

$ java8
$ java -version
java version "1.8.0_261"

Old Guide if you have old Homebrew and MacOS versions...

I will share my experiences with macOS Big Sur v11.4, the best way to deal with these problems is by installing Java using Homebrew:

1 - Install Homebrew.

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

2 - Install Homebrew Cask.

$ brew tap homebrew/cask-versions 
$ brew update 
$ brew tap homebrew/cask

3 - Install the latest version of Java

$ brew cask install java

4 - Install the other needed versions of Java (Java8, Java11, Java13).

$ brew tap adoptopenjdk/openjdk

$ brew cask install adoptopenjdk8
$ brew cask install adoptopenjdk11
$ brew cask install adoptopenjdk13
$ brew cask install adoptopenjdk14

5 - Switch between different versions of Java

Switching between different versions of Java, you only need to add the following to your .bash_profile or .zshrc.

In this case, we want to be able to switch between Java8, Java11, Java13 and Java14:

export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)
export JAVA_11_HOME=$(/usr/libexec/java_home -v11)
export JAVA_13_HOME=$(/usr/libexec/java_home -v13)
export JAVA_14_HOME=$(/usr/libexec/java_home -v14)

alias java8='export JAVA_HOME=$JAVA_8_HOME'
alias java11='export JAVA_HOME=$JAVA_11_HOME'
alias java13='export JAVA_HOME=$JAVA_13_HOME'
alias java14='export JAVA_HOME=$JAVA_14_HOME'

# default to Java 14
java14

6 - Reload .bash_profile or .zshrc for the aliases to take effect:

$ source ~/.bash_profile

or

$ source ~/.zshrc

7 - Finally you can use the aliases to switch between different Java versions.

$ java8
$ java -version
java version "1.8.0_261"

For more info, you can see this post: How to Use Brew to Install Java on Mac

Answer 5

A small fish function based on /usr/libexec/java_home

function jhome
    set JAVA_HOME (/usr/libexec/java_home $argv)
    echo "JAVA_HOME:" $JAVA_HOME
    echo "java -version:"
    java -version
end

If you don't use fish, you can do something similar in bash:

#!/bin/bash

jhome () {
  export JAVA_HOME=`/usr/libexec/java_home $@`
  echo "JAVA_HOME:" $JAVA_HOME
  echo "java -version:"
  java -version
}

Then to switch between javas do:

$> jhome           #switches to latest java
$> jhome -v 1.7    #switches to java 1.7
$> jhome -v 1.6    #switches to java 1.6

ref: https://gist.github.com/kenglxn/1843d552dff4d4233271

Answer 6

Use jenv is an easy way. (Update 2022)

1. Install jenv: see Getting started

2. Install java with brew

   brew install openjdk@11
   ln -s /usr/local/opt/openjdk@11/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk-11.jdk
   
   #other java
   brew install openjdk@8
   brew install openjdk@17
   

3. Add java to jenv

   jenv add /Library/Java/JavaVirtualMachines/openjdk-11.jdk/Contents/Home
   

4. Use: refer to jenv

Answer 7

install JDK, not just JRE

/usr/libexec/java_home -v 1.8

gives

/Library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home

next

touch .bash_profile

open -a TextEdit.app .bash_profile

TextEdit will show you a blank page which you can fill in.

add to doc: export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_111.jdk/Contents/Home

in terminal:

export JAVA_HOME="$(/usr/libexec/java_home -v 1.8)"

try the command:

javac -version

should output:

javac 1.8.0_111

Answer 8

It is a little bit tricky, but try to follow the steps described in Installing Java on OS X 10.9 (Mavericks). Basically, you gonna have to update your alias to java.

Step by step:

After installing JDK 1.7, you will need to do the sudo ln -snf in order to change the link to current java. To do so, open Terminal and issue the command:

sudo ln -nsf /Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents \
/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK

Note that the directory jdk1.7.0_51.jdk may change depending on the SDK version you have installed.

Now, you need to set JAVA_HOME to point to where jdk_1.7.0_xx.jdk was installed. Open again the Terminal and type:

export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home"

You can add the export JAVA_HOME line above in your .bashrc file to have java permanently in your Terminal

Answer 9

tl;dr

Add the line:

export JAVA_HOME='/Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home'

to the file

~/.bash_profile

(replace jdk1.8.0_144.jdk with your downloaded version)

then source ~/.bash_profile

Answer 10

Use jenv, it is like a Java environment manager. It is super easy to use and clean

For Mac, follow the steps:

brew install jenv

git clone https://github.com/gcuisinier/jenv.git ~/.jenv

Installation: If you are using bash follow these steps:

$ echo 'export PATH="$HOME/.jenv/bin:$PATH"' >> ~/.bash_profile

echo 'eval "$(jenv init -)"' >> ~/.bash_profile

$ exec $SHELL -l

Add desired versions of JVM to jenv:

jenv add /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

jenv add /System/Library/Java/JavaVirtualMachines/1.8.0.jdk/Contents/Home

Check the installed versions:

jenv versions

Set the Java version you want to use by:

jenv global oracle64-1.6.0

Answer 11

Run

/usr/libexec/java_home -V

you will get all the java version that you have

Example:-

Matching Java Virtual Machines (3):
    17.0.7 (x86_64) "Amazon.com Inc." - "Amazon Corretto 17" /Library/Java/JavaVirtualMachines/amazon-corretto-17.jdk/Contents/Home
    11.0.19 (x86_64) "Amazon.com Inc." - "Amazon Corretto 11" /Users/abhishek.khaiwale/Library/Java/JavaVirtualMachines/corretto-11.0.19/Contents/Home
    11.0.19 (x86_64) "Amazon.com Inc." - "Amazon Corretto 11" /Library/Java/JavaVirtualMachines/amazon-corretto-11.jdk/Contents/Home

If you need java version 11.0.19

Run

export JAVA_HOME=`/usr/libexec/java_home -v 11.0.19`

Youtube Video Link

Answer 12

Consider the following approach only to change the JDK for each and specific tab of your terminal (i.e: iTerm).

Having in the /Library/Java/JavaVirtualMachines path the two following jdks

• openjdk8u275-b01
• openjdk-11.0.9.1+1

And in the .bash_profile file the following:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/openjdk-11.0.9.1+1/Contents/Home
export PATH=$JAVA_HOME/bin:$PATH

If you open Iterm - with the first Tab A - and the following commands are executed:

javac -version
javac 11.0.9.1

java -version
openjdk version "11.0.9.1" 2020-11-04
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.9.1+1)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.9.1+1, mixed mode)

The output is correct and expected

But if you open a second Tab B and you need override the default JDK then write in the terminal the following:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/openjdk8u275-b01/Contents/Home/
export PATH=$JAVA_HOME/bin:$PATH

Then

javac -version
javac 1.8.0_275

java -version
openjdk version "1.8.0_275"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_275-b01)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.275-b01, mixed mode)

It works fine. Of course if the Tab B is closed or you open a new Tab C all work according the .bash_profile settings (therefore the default settings)

Answer 13

macOS El Capitan or newer will choose the higher version of the JDK available in /Library/Java/JavaVirtualMachines, so in order to downgrade you may rename the file Info.plist to something else like Info.plist.disabled so that the OS will choose a previous version.

Answer 14

Four easy steps using terminal for people who uses the default process.. :)

1. echo $JAVA_HOME gives you current java home. For eg: /Library/Java/JavaVirtualMachines/jdk1.8.0_191.jdk/Contents/Home/

2. cd /Library/Java/JavaVirtualMachines/ will take you to the folder where u normally install jdks (It might be different for your machines)

3. ls shows you available folders (normally it will have the version numbers, for eg: jdk1.8.0_191.jdk openjdk-11.0.2.jdk)
4. export JAVA_HOME='/Library/Java/JavaVirtualMachines/openjdk-11.0.2.jdk/Contents/Home' will change the java home..

Answer 15

function setjdk() {
  if [ $# -ne 0 ]; then
    removeFromPath '/System/Library/Frameworks/JavaVM.framework/Home/bin'
    if [ -n "${JAVA_HOME+x}" ]; then
      removeFromPath $JAVA_HOME
    fi
    export JAVA_HOME=`/usr/libexec/java_home -v $@`
    export PATH=$JAVA_HOME/bin:$PATH
  fi
}

put this in your ~/.profile and use it in your terminal like so setjdk 1.8, setjdk 1.7, setjdk 9 etc etc...

If you don't have removeFromPath then it is:

function removeFromPath() { export PATH=$(echo $PATH | sed -E -e "s;:$1;;" -e "s;$1:?;;") }

Answer 16

You can add it to your .bash_profile to have the version set by default.

//Open bash profile
open ~/.bash_profile

export JAVA_HOME=`/usr/libexec/java_home -v 1.8`

// run bash profile
source ~/.bash_profile

Answer 17

Add following in your ~/.bash_profile and set the default java version accordingly.

export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)
export JAVA_11_HOME=$(/usr/libexec/java_home -v11)

alias java8='export JAVA_HOME=$JAVA_8_HOME'
alias java11='export JAVA_HOME=$JAVA_11_HOME'

# default to Java 8
java8

I am using macOS and have installed java using brew.

Edit: If you are not using bash please update the correct shell file, example, if you are using zsh then it will be ~/.zshrc

Answer 18

add following command to the ~/.zshenv file

export JAVA_HOME=`/usr/libexec/java_home -v 1.8` 

Answer 19

1. Add the following line of code to your .zshrc (or bash_profile):

alias j='f(){ export JAVA_HOME=/usr/libexec/java_home -v $1 };f'

2. Save to session:

$ source .zshrc

3. Run command (e.g. j 13, j14, j1.8...)

$ j 1.8

Explanation This is parameterised so you do not need to update the script like other solutions posted. If you do not have the JVM installed you are told. Sample cases below:

/Users/user/IDE/project $ j 1.8
/Users/user/IDE/project $ java -version
openjdk version "1.8.0_265"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_265-b01)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.265-b01, mixed mode)
/Users/user/IDE/project $ j 13
/Users/user/IDE/project $ java -version
openjdk version "13.0.2" 2020-01-14
OpenJDK Runtime Environment (build 13.0.2+8)
OpenJDK 64-Bit Server VM (build 13.0.2+8, mixed mode, sharing)
/Users/user/IDE/project $ j 1.7
Unable to find any JVMs matching version "1.7".

Answer 20

Check Java version: java -version

Switch between versions: https://devqa.io/brew-install-java/

open ~/.bash_profile

export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)

export JAVA_11_HOME=$(/usr/libexec/java_home -v11)

alias java8='export JAVA_HOME=$JAVA_8_HOME' alias java11='export JAVA_HOME=$JAVA_11_HOME'

source ~/.bash_profile

When we are switching to java11 or java8, java -version command is not showing the correct version.

In that case use mvn -version to see the correct java version is used for building the solution

Answer 21

From the Apple's official java_home(1) man page:

**USAGE**

   /usr/libexec/java_home  helps  users  set a $JAVA_HOME in their login rc files, or provides a way for
   command-line Java tools to use the most appropriate JVM which can satisfy a minimum version or archi-
   tecture  requirement.  The --exec argument can invoke tools in the selected $JAVA_HOME/bin directory,
   which is useful for starting Java command-line tools from launchd plists without hardcoding the  full
   path to the Java command-line tool.

   Usage for bash-style shells:
          $ export JAVA_HOME=`/usr/libexec/java_home`

   Usage for csh-style shells:
          % setenv JAVA_HOME `/usr/libexec/java_home`

Answer 22

JDK Switch Script

I have adapted the answer from @Alex above and wrote the following to fix the code for Java 9.

$ cat ~/.jdk
#!/bin/bash

#list available jdks
alias jdks="/usr/libexec/java_home -V"
# jdk version switching - e.g. `jdk 6` will switch to version 1.6
function jdk() {
  echo "Switching java version $1";

  requestedVersion=$1
  oldStyleVersion=8
  # Set the version
  if [ $requestedVersion -gt $oldStyleVersion ]; then
    export JAVA_HOME=$(/usr/libexec/java_home -v $1);
  else
    export JAVA_HOME=`/usr/libexec/java_home -v 1.$1`;
  fi

  echo "Setting JAVA_HOME=$JAVA_HOME"

  which java
  java -version;
}

Switch to Java 8

$ jdk 8
Switching java version 8
Setting JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_131.jdk/Contents/Home
/usr/bin/java
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

Switch to Java 9

$ jdk 9
Switching java version 9
Setting JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-9.0.1.jdk/Contents/Home
/usr/bin/java
java version "9.0.1"
Java(TM) SE Runtime Environment (build 9.0.1+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.1+11, mixed mode)

Answer 23

Previously I used alias'es in .zshrc for easy switching between versions but today I use SDKMAN. SDKMAN can also handle setting default java for the system, and downloading and installing new java versions.

Once sdkman is installed you can then do commands similar to what is possible with the nvm tool for handling node versions.

sdk list java will list the java versions available on your system as well as available online for installation including their identifier that you can use in the sdk use, sdk default and sdk install commands.

e.g. to install Amazon Corretto 11.0.8 and ask if it should be the new default do this: sdk install java 11.0.8-amzn

A feature I also use regularly is the .sdkmanrc file. If you place that in a directory on your machine and run the sdk env command in the directory then you can configure tool versions used only in that directory. It is also possible to make sdkman switch tool versions automatically using the sdkman_auto_env=true configuration.

sdkman also supports handling other tools for the JVM such as gradle, kotlin, maven and more.

For more information check out https://sdkman.io/usage#env

Answer 24

With no additional tools to install, an easy way to have a separately installed JDK recognized as a first class member by /usr/libexec/java_home -V is to symlink it as follows:

sudo ln -s <path> /Library/Java/JavaVirtualMachines/jdk-[some-identifier].jdk

<path> is expected to be a directory containing subdirectories Contents/Home/bin etc.

---

A common use case is to register the JDK/JRE included with Android Studio:

The default location for the Java tools in recent versions of Android Studio on macOS is /Applications/Android\ Studio.app/Contents/jre. We will use jdk-android-studio.jdk as the identifier:

sudo ln -s /Applications/Android\ Studio.app/Contents/jre /Library/Java/JavaVirtualMachines/jdk-android-studio.jdk

Now, /usr/libexec/java_home -V will list it under Matching Java Virtual Machines:

$ /usr/libexec/java_home -V
Matching Java Virtual Machines (1):
    11.0.13 (arm64) "JetBrains s.r.o." - "OpenJDK 11.0.13" /Applications/Android Studio.app/Contents/jre/Contents/Home
/Applications/Android Studio.app/Contents/jre/Contents/Home

Answer 25

If still u are not able to set it. using this command.

export JAVA_HOME=/usr/libexec/java_home -v 1.8

then you have to use this one.

export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)

it will surely work.

Answer 26

First find out where do you store the environment variables-

1. emacs
2. bash_profile
3. zshrc file

Steps to Set up the environment variable :-

1. Download the jdk from JAVA

2. install it by double click

3. Now set-up environment variables in your file

   a. For emacs.profile you can use this link OR see the screenshot below

b. For ZSH profile setup -

1. export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home

2. source ~/.zshrc - Restart zshrc to reflect the changes.

3. echo $JAVA_HOME - make sure path is set up properly 
   ----> /Library/Java/JavaVirtualMachines/jdk1.8.0_112.jdk/Contents/Home

4. java -version 

   -->  java version "1.8.0_112"  Java(TM) SE Runtime Environment (build 1.8.0_112-b16)Java HotSpot(TM) 64-Bit Server VM (build 25.112-b16, mixed mode)

All set Now you can easily upgrade or degrade the JAVA version..

Answer 27

If you are using fish and you are using mac and you want to be able to switch between JDK's, then below works for me on mac.

@kenglxn's answer didn't work for me and I figured out it bcos didn't set -g which is global !

Put below under ~/.config/fish/config.fish

alias j8="jhome  -v 1.8.0_162"
alias j9="jhome  -v 9.0.1"

function jhome
    set -g -x JAVA_HOME (/usr/libexec/java_home $argv)
    echo "JAVA_HOME:" $JAVA_HOME
    echo "java -version:"
    java -version
end

funcsave jhome

To know which version /minor version you have installed, you can do :

/usr/libexec/java_home -V                                                                              579ms  Wed 14 Feb 11:44:01 2018
Matching Java Virtual Machines (3):
    9.0.1, x86_64:  "Java SE 9.0.1" /Library/Java/JavaVirtualMachines/jdk-9.0.1.jdk/Contents/Home
    1.8.0_162, x86_64:  "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_162.jdk/Contents/Home
    1.8.0_121, x86_64:  "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0_121.jdk/Contents/Home

Answer 28

If you have multiple versions and you want to run something by using a specific version, use this example:

/usr/libexec/java_home -v 1.7.0_75 --exec java -jar you-file.jar

Answer 29

Based on @markhellewell answer I created a couple of alias functions that will do it for you. Just add these to your shell startup file

#list available jdks
alias jdks="/usr/libexec/java_home -V"
# jdk version switching - e.g. `jdk 6` will switch to version 1.6
function jdk() { 
  echo "Switching java version"; 
  export JAVA_HOME=`/usr/libexec/java_home -v 1.$1`; 
  java -version; 
}

https://gist.github.com/Noyabronok/0a90e1f3c52d1aaa941013d3caa8d0e4

Answer 30

Here is how I do it on my Linux (Ubuntu / Mint mate), I guess Mac can do it similarly.

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Install & config

Steps:

• [Basic - part]
• Download jdk (the .tgz file) by hand.
• Uncompress & rename properly, at a proper location.
  e.g /mnt/star/program/java/jdk-1.8
• Make a soft link, which will be changed to switch java version later.
  e.g ln -s /mnt/star/program/java/jdk-1.8 /mnt/star/program/java/java
  Thus /mnt/star/program/java/java is the soft link.
• Set JAVA_HOME in a start script.
  Could use file like /etc/profile.d/eric.sh, or just use ~/.bashrc.
  e.g JAVA_HOME=/mnt/star/program/java/java
• Then open a new bash shell. java -version should print the java version.
• [More version - part]
• Download & install more Java version, as need, similar as above steps.
  e.g
  /mnt/star/program/java/jdk-11
• [Switch - part]
• In ~/.bashrc, define variable for various Java version.
  e.g
  _E_JAVA_HOME_11='/mnt/star/program/java/jdk-11'
_E_JAVA_HOME_8='/mnt/star/program/java/jdk-8'
# dir of default version,
_E_JAVA_HOME_D=$_E_JAVA_HOME_8
• In ~/.bashrc, define command to switch Java version.
  e.g
  ## switch java version,
alias jv11="rm $JAVA_HOME; ln -s $_E_JAVA_HOME_11 $JAVA_HOME"
alias jv8="rm $JAVA_HOME; ln -s $_E_JAVA_HOME_8 $JAVA_HOME"
# default java version,
alias jvd="rm $JAVA_HOME; ln -s $_E_JAVA_HOME_D $JAVA_HOME"
alias jv="java -version"
• In terminal, source ~/.bashrc to make the changes take effect.
• Then could switch using the defined commands.

---

Commands - from above config

Commands:

• jv11
  Switch to Java 11
• jv8
  Switch to Java 8
• jvd
  Switch to default Java version, which is denoted by _E_JAVA_HOME_D defined above.
• jv
  Show java version.

Example output:

eric@eric-pc:~$ jv
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

eric@eric-pc:~$ jv11
eric@eric-pc:~$ jv
java version "11.0.1" 2018-10-16 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.1+13-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.1+13-LTS, mixed mode)

eric@eric-pc:~$ jvd
eric@eric-pc:~$ jv
java version "1.8.0_191"
Java(TM) SE Runtime Environment (build 1.8.0_191-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)

eric@eric-pc:~$ 

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Mechanism

• It switch by changing the soft link, which is used as JAVA_HOME.

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Tips

• On my machine when install jdk by hand, I keep the minor version, then make a soft link with the major version but without the minor version.
  e.g
  // this is the actual dir,
  jdk1.8.0_191

  // this is a soft link to jdk1.8.0_191
jdk-8

  // this is a soft link to jdk-8 or jdk-11
java

• I define command alias in ~/.bashrc, but define variable in a separate file.
  I am using ~/.eric_var to define the variables, and ~/.bashrc will source it (e.g source $HOME/.eric_var).