Unable to understand what jdk location is

I have java installed correctly for sure.

aaa@ubuntu:~$ whereis java
java: /usr/bin/java /usr/bin/X11/java /usr/local/java /usr/share/java
aaa@ubuntu:~$ whereis javac
javac: /usr/bin/javac /usr/bin/X11/javac

But when I'm trying to add the location of /usr/bin/java in IntellyJ Idea12 as a java project sdk, I can't do that because it requires the folder and /usr/bin/java is a file. Even if I specify /usr/bin, it says that it's not a valid location.

So where is it located and how do I setup a location to be a java sdk for IntellyJ Idea12 or for Eclipse?

UPDATE: The path "/usr/lib/jvm/" doesn't exist

UPDATE2:

I used this tutorial http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux

All ubuntu JRE and JDK installs gets stored in /usr/lib/jvm/.

You need to add the multi-arch specific JDK location to Idea12. For example, on 32-bit x86 Ubuntu installations, use /usr/lib/jvm/java-7-openjdk-i386.