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How can I change Mac OS's default Java VM returned from /usr/libexec/java_home

Posted by: admin November 30, 2017 Leave a comment

Questions:

(Wasn’t sure if this should go on SU… migration is certainly an option, but more programmers read questions here, so here goes).

I am running Mac OS X 10.8.4, and I have Apple’s JDK 1.6.0_51 installed as well as Oracle’s JDK 1.7.0_25. I recently installed Oracle’s 1.8 preview JDK for some pre-release software that requires it. Now, when I run /usr/libexec/java_home, I get this:

$ /usr/libexec/java_home -V
Matching Java Virtual Machines (4):
    1.8.0, x86_64:  "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home
    1.7.0_25, x86_64:   "Java SE 7" /Library/Java/JavaVirtualMachines/jdk1.7.0_25.jdk/Contents/Home
    1.6.0_51-b11-457, x86_64:   "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
    1.6.0_51-b11-457, i386: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

Great.

However, running:

$ java -version

Returns:

java version "1.8.0-ea"

That means that the default version of Java is currently the pre-release version, which breaks some “normal” packages (in my case, VisualVM).

I can’t set JAVA_HOME because launching applications ignores environment variables, even when launching from the command line (e.g. $ open /Applications/VisualVM.app).

So, is there a file I can edit where I can set my JVM ordering preferences globally?

(Please don’t tell me to launch the Java Preferences Panel because that simply does not work: it does not contain anything useful and only lists one of the 4 JVMs that I have installed.)

Update:

Oracle JVMs live in /Library/Java/JavaVirtualMachines. Re-naming the JDK 1.8 directory to jdk1.8.0.jvm.xyz does not change anything: java_home still finds it in the right place, and running /usr/bin/java still executes the 1.8 JVM. This is not an issue with synlinks, etc.

Answers:

I think JAVA_HOME is the best you can do. The command-line tools like java and javac will respect that environment variable, you can use /usr/libexec/java_home -v '1.7*' to give you a suitable value to put into JAVA_HOME in order to make command line tools use Java 7.

export JAVA_HOME="`/usr/libexec/java_home -v '1.7*'`"

But standard double-clickable application bundles don’t use JDKs installed under /Library/Java at all. Old-style .app bundles using Apple’s JavaApplicationStub will use Apple Java 6 from /System/Library/Frameworks, and new-style ones built with AppBundler without a bundled JRE will use the “public” JRE in /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home – that’s hard-coded in the stub code and can’t be changed, and you can’t have two different public JREs installed at the same time.


Edit: I’ve had a look at VisualVM specifically, assuming you’re using the “application bundle” version from the download page, and this particular app is not an AppBundler application, instead its main executable is a shell script that calls a number of other shell scripts and reads various configuration files. It defaults to picking the newest JDK from /Library/Java as long as that is 7u10 or later, or uses Java 6 if your Java 7 installation is update 9 or earlier. But unravelling the logic in the shell scripts it looks to me like you can specify a particular JDK using a configuration file.

Create a text file ~/Library/Application Support/VisualVM/1.3.6/etc/visualvm.conf (replace 1.3.6 with whatever version of VisualVM you’re using) containing the line

visualvm_jdkhome="`/usr/libexec/java_home -v '1.7*'`"

and this will force it to choose Java 7 instead of 8.

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I’ve been there too and searched everywhere how /usr/libexec/java_home works but I couldn’t find any information on how it determines the available Java Virtual Machines it lists.

I’ve experimented a bit and I think it simply executes a ls /Library/Java/JavaVirtualMachines and then inspects the ./<version>/Contents/Info.plist of all runtimes it finds there.

It then sorts them descending by the key JVMVersion contained in the Info.plist and by default it uses the first entry as its default JVM.

I think the only thing we might do is to change the plist: sudo vi /Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Info.plist and then modify the JVMVersion from 1.8.0 to something else that makes it sort it to the bottom instead of the top, like !1.8.0.

Something like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    ...
    <dict>
            ...
            <key>JVMVersion</key>
            <string>!1.8.0</string>   <!-- changed from '1.8.0' to '!1.8.0' -->`

and then it magically disappears from the top of the list:

/usr/libexec/java_home -verbose
Matching Java Virtual Machines (3):
    1.7.0_45, x86_64:   "Java SE 7" /Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home
    1.7.0_09, x86_64:   "Java SE 7" /Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home
    !1.8.0, x86_64: "Java SE 8" /Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home

Now you will need to logout/login and then:

java -version
java version "1.7.0_45"

🙂

Of course I have no idea if something else breaks now or if the 1.8.0-ea version of java still works correctly.

You probably should not do any of this but instead simply deinstall 1.8.0.

However so far this has worked for me.

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Answers:

Oracle’s uninstallation instructions for Java 7 worked for me.

Excerpt:

Uninstalling the JDK
To uninstall the JDK, you must have Administrator privileges and execute the remove command either as root or by using the sudo(8) tool.

Navigate to /Library/Java/JavaVirtualMachines and remove the directory whose name matches the following format:*

/Library/Java/JavaVirtualMachines/jdk<major>.<minor>.<macro[_update]>.jdk

For example, to uninstall 7u6:

% rm -rf jdk1.7.0_06.jdk

Questions:
Answers:

A bit late but as this is an ongoing issue with Mac OSX…

The simplest solution I found was to simply remove the OpenJDK stuff that Apple installs. Every time an update of Mac OSX arrives it gets installed and you’ll need to remove it again.

This works really well if you develop apps for Google App Engine on your mac using Java. The OpenJDK does not work well and the Java version that comes with the Mac OSX Yosemite upgrade will make the Eclipse Plug-in for App Engine crash on every deployment with the helpful error: “Read timed out”.

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It’s actually pretty easy.
Let’s say we have this in our JavaVirtualMachines folder:

  • jdk1.7.0_51.jdk
  • jdk1.8.0.jdk

Imagine that 1.8 is our default, then we just add a new folder (for example ‘old’) and move the default jdk folder to that new folder.
Do java -version again et voila, 1.7!

Questions:
Answers:

It’s pretty simple, if you don’t mind rolling up your sleeves… /Library/Java/Home is the default for JAVA_HOME, and it’s just a link that points to one of:

  • /System/Library/Java/JavaVirtualMachines/1.?.?.jdk/Contents/Home
  • /Library/Java/JavaVirtualMachines/jdk1.?.?_??.jdk/Contents/Home

So I wanted to change my default JVM/JDK version without changing the contents of JAVA_HOME… /Library/Java/Home is the standard location for the current JVM/JDK and that’s what I wanted to preserve… it seems to me to be the easiest way to change things with the least side effects.

It’s actually really simple. In order to change which version of java you see with java -version, all you have to do is some version of this:

cd /Library/Java
sudo rm Home
sudo ln -s /Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home ./Home

I haven’t taken the time but a very simple shell script that makes use of /usr/libexec/java_home and ln to repoint the above symlink should be stupid easy to create…

Once you’ve changed where /Library/Java/Home is pointed… you get the correct result:

cerebro:~ magneto$ java -version
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27) Java HotSpot(TM)
64-Bit Server VM (build 25.60-b23, mixed mode)

Questions:
Answers:

I had a similar situation, and the following process worked for me:

  1. In the terminal, type

    vi ~/.profile
    
  2. Then add this line in the file, and save

    export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk<version>.jdk/Contents/Home
    

    where version is the one on your computer, such as 1.7.0_25

  3. Exit the editor, then type the following command make it become effective

    source ~/.profile 
    

Then type java -version to check the result

    java -version 

What is .profile?
From:http://computers.tutsplus.com/tutorials/speed-up-your-terminal-workflow-with-command-aliases-and-profile–mac-30515

.profile file is a hidden file. It is an optional file which tells the system which commands to run when the user whose profile file it is logs in. For example, if my username is bruno and there is a .profile file in /Users/bruno/, all of its contents will be executed during the log-in procedure.

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Answers:

MacOS uses /usr/libexec/java_home to find the current Java Version. One way to bypass is to change the plist file as explained by @void256 above.
Other ways is to take the backup of the java_home and replace it with your own script java_home having the code
echo $JAVA_HOME

Now export the JAVA_HOME to the desired version of the SDK by adding the following commands to the ~/.bash_profile.
export JAVA_HOME=”/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home”
launchctl setenv JAVA_HOME $JAVA_HOME /// Make the environment variable global

Run the command source ~/.bash_profile to the run the above commands.

Anytime one needs to change the JAVA_HOME he can reset the JAVA_HOME value in the ~/.bash_profile file.

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Edit: this information is for visualvm specifically, not for any other java app

As mentioned by others, you need to modify the visualvm.conf

For the latest version of JvisualVM 1.3.6 on Mac, the install directories have changed.

It is currently in
/Applications/VisualVM.app/Contents/Resources/visualvm/etc/visualvm.conf.

However this may depend on where you have installed VisualVM. The easiest way to find where your VisualVM is to start it, and then look at the process using:

ps -ef | grep VisualVM

You will see something like:

-Dnetbeans.dirs=/Applications/VisualVM.app/Contents/Resources/visualvm/visualvm

You want to take the netbeans.dir property and look up a directory and you will find the etc folder.

Uncomment this line in the visualvm.conf and change the path to the jdk

visualvm_jdkhome="/path/to/jdk"

Additionally, if you are having slowness with your visualvm and you have a lot of memory, I would suggest greatly increasing the amount of memory available and running it in server mode:

visualvm_default_options="-J-XX:MaxPermSize=96m -J-Xmx2048m -J-Xms2048m -J-server -J-XX:+UseCompressedOops -J-XX:+UseConcMarkSweepGC -J-XX:+UseParNewGC -J-XX:NewRatio=2 -J-Dnetbeans.accept_license_class=com.sun.tools.visualvm.modules.startup.AcceptLicense -J-Dsun.jvmstat.perdata.syncWaitMs=10000 -J-Dsun.java2d.noddraw=true -J-Dsun.java2d.d3d=false"

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I wanted to change default java version form 1.6* to 1.7*. I tried the following steps and it worked for me:

  • Removed link “java” from under /usr/bin
  • Created it again, pointing to the new location:

ln -s /Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/java java

  • verified with “java -version”

java version “1.7.0_51”
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)