Usability Improvement: Support /usr/libexec/java_home to find path for JDK on macOS

[johanneshoehn]

On macOS there is a standard way to find the location of the JDK, invoking /usr/libexec/java_home:
http://stackoverflow.com/questions/18144660/what-is-path-of-jdk-on-mac
https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man1/java_home.1.html

I was a bit confused that vscode-java didn't work out of the box (also no apparent error message, just a message about installing something in the corner that didn't change. I had to set java.home in the settings to the value returned by /usr/libexec/java_home and then it worked. I guess this should be true on most macOS systems and vscode-java could use it directly to find the java home path, making installation easier.

[gorkem]

We are actually using a utility to resolve JAVA_HOME which in turn seems to be using the mac utility that you have mentioned.

Does your JAVA_HOME (the value returned from mac utility) point to a JRE or JDK?

[johanneshoehn]

JAVA_HOME is not set. I tried doing the same thing as the library does and it should work:

 > env | grep JAVA
 > which javac
/usr/bin/javac
 > readlink /usr/bin/javac
/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/javac
 > ls /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/ | grep home
java_home
 > /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java_home
/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home
 > /usr/libexec/java_home
/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home

When I remove "java.home": "/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home" from my settings.json again, the status bar keeps says again "Starting Java Language Server...".

Edit: Maybe as an additional help for finding out where exactly things break. The ~/.vscode/extensions/redhat.java-0.0.5/server/ folder was still empty before I set java.home for the first time.

[johanneshoehn]

I guess the bug is here:

vscode-java/src/requirements.ts

Line 71 in 810cc60

process.env['JAVA_HOME'] = javaHome;

This always sets the JAVA_HOME environmental variable, even if there isn't a correct one found. find-java-home then takes this variable and returns it as a valid java home directory.