I installed the JDK by downloading the dmg from the Oracle website here: http://www.oracle.com/technetwork/java/javase/downloads/jdk7u9-downloads-1859576.html
For me, I had to select Project Structure->Platform Setting->Global Libraries and click on the "+" icon that is at the top of the middle pane of the Project Structure window. This brings up a "New Global Library" drop down menu. From there I was able to locate the libraries I wanted to include.