Biomart 0.8 :: Ant :: Build Failed

$ git clone https://github.com/biomart/biomart-rc6.git
biomart-rc6/
$ cd biomart-rc6/
$ ant
:
[mkdir] Created dir: /home/user/Desktop/biomart-rc6/dist/registry/linkindices
:

BUILD FAILED
/home/user/Desktop/biomart-rc6/build.xml:33: Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK.
It is currently set to "/usr/lib/jvm/java-7-openjdk-amd64/jre"

On Linux machine when I installed openjdk, it had only installed jre.

To install jdk from openjdk

$ sudo apt-get install openjdk-7-jdk

I rerun the ant command

$ ant

BUILD SUCCESSFUL