I was getting the following error when attempting to run hadoop version.

The java class is not found: org.apache.hadoop.util.VersionInfo
Unable to determine Hadoop version information.
'hadoop version' returned:
The java class is not found: org.apache.hadoop.util.VersionInfo

This was due to having the OpenJDK installed rather than the one from Sun/Oracle. To resolve this simply uninstall the openjdk packages…

sudo zypper remove java

Download one of the Sun/Oracle java packages for your platform. I installed it with…

sudo rpm -iv jdk-7u11-linux-x64.rpm

I also had to set my java home to /usr. Remember to set this is your .profile or somewhere else appropriate. Now when I run hadoop version I get…

Hadoop 2.0.2-alpha
Subversion https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.0.2-alpha/hadoop-common-project/hadoop-common -r 1392682
Compiled by hortonmu on Tue Oct  2 00:44:10 UTC 2012
From source with checksum efbdb59af73bfc103f1945d65dbf3071

Happy Hadoop’ing!