Try the following to see if you have the proper repository installed:
# yum search java | grep 'java-'
This is going to return a list of available packages that have java in the title. Specifically we are interested in the java- anything, as the jdk will typically be in 'java-version#' type format... Anyhow, if you have to install a repo look at Dag Wieers repo:
http://dag.wieers.com/rpm/FAQ.php#B
After you've got it installed try yum search again... This time you'll have a bunch of java stuff.
# yum search java | grep 'java-'
This will return the list of the available java packages. You can install one like this:
# yum install java-1.7.0-openjdk.x86_64