· java

Java: Finding/Setting JDK/$JAVA_HOME on Mac OS X

As long as I've been using a Mac I always understood that if you needed to set $JAVA_HOME for any program, it should be set to /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK.

On my machine this points to the 1.6 JDK:


$ ls -alh /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK
/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK -> /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents

This was a bit surprising to me since I've actually got Java 7 installed on the machine as well so I'd assumed the symlink would have been changed:


$ java -version
java version "1.7.0_09"
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) 64-Bit Server VM (build 23.5-b02, mixed mode)

Andres and I were looking at something around this yesterday and wanted to set $JAVA_HOME to the location of the 1.7 JDK on the system if it had been installed.

We eventually came across the following article which explains that you can use the /usr/libexec/java_home command line tool to do this.

For example, if we want to find where the 1.7 JDK is we could run the following:


$ /usr/libexec/java_home -v 1.7
/Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home

And if we want 1.6 the following does the trick:


$ /usr/libexec/java_home -v 1.6
/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

We can also list all the JVMs installed on the machine:


$ /usr/libexec/java_home  -V
Matching Java Virtual Machines (3):
    1.7.0_09, x86_64:	"Java SE 7"	/Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home
    1.6.0_45-b06-451, x86_64:	"Java SE 6"	/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
    1.6.0_45-b06-451, i386:	"Java SE 6"	/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home

/Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home

I'm not sure how I've never come across this command before but it seems pretty neat.

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