My son and I have been working our way through the book, "Minecraft Modding with Forge", only to get stuck on page six for quite a while.  We found lots of people encountering the same error, but no solutions.  Tonight, I was determined to get it to work, and here is how I did it!

 

The first step can be done with your regular user account:

 

1. Download Minecraft Forge from http://files.minecraftforge.net (get the "recommended version"--at the time of this post, 11.14.4.1563 (the Mdk one)).

 

2. You should now have a 'Forge' directory in your 'Downloads' folder (mine was actually named 'Forge-1').  Make a folder on your Desktop called 'forge' and copy the contents of the Download 'Forge' directory into the 'forge' directory on your Desktop.

 

Note: These next few steps need to be run under an Administrator account:

 

3. Install "brew" from http://brew.sh, which you can use to easily install an older version of Java SDK (1.6)

 

4. Install Java SDK 1.6 by typing the following into the 'Terminal' program:

 

brew tap cask room/versions

brew cask install java6

 

5. Delete the 'vecmath.jar' file in /System/Library/Java/Extensions (if you don't have a copy of 'vecmath.jar' at this location, that is ok)

 

Now go back to your regular user account

 

6. Set your JAVA_HOME environment variable, again using the "Terminal" program:

 

export JAVA_HOME=$(/usr/libexec/java_home -v 1.6)

 

7. Change directories to your Desktop 'forge' directory

 

8. Edit the 'gradlew' file.  Change the DEFAULT_JVM_OPTS="" line to DEFAULT_JVM_OPTS="-Xmx1024m"

 

9. You're now ready to run the command:

 

./gradlew setupDecompWorkspace eclipse

 

I got the desired "BUILD SUCCESSFUL" message after about 5 minutes and 30 seconds.  If you get past the 'recompileMc' task, you should be home free.

 

I really hope this helps others who are working with the book, or trying to get Forge to work on OSX.  It can be done!  Don't give up!

 

[My System Specs]

 

OS X Yosemite (version 10.10.5)

Mac mini (Late 2009)

Processor 2.66 GHz Intel Core 2 Duo

Memory 8GB 1067 Mhz DDR3

Graphics NVIDIA GeForce 9400 256MB

Using Java SDK 1.6 co-installed with Java SDK 1.8

JAVA_HOME set using /usr/libexec/java_home -v 1.6

 

I agree, but after a month of trying to get it to work with 1.8, I decided to try 1.6, since that is the version the script complained about not having when I ran it. 

I couldn't even get past deleting the file...

I get the error message "unable to delete vecmath.jar as it is used by OSX"

 

can I get it to work whit java 8 or most I hava java 6 because I don't find ware I can download it