By default your Fedora Linux system comes with a OpenJDK Java fetched from a standard Fedora repository. You may have some reasons to switch from OpenJDK to Oracle Java JRE. In order to achieve this firs download a java binary form oracle website:
http://www.oracle.com/technetwork/java/javase/downloads/index.html
as a root user make jre binary executable:
# chmod +x jre-6u23-linux-i586.bin
and execute the binary with:
# ./jre-6u23-linux-i586.bin
Switch over from OpenJDK to Oracle JRE: The above command extracted all content of jre-6u23-linux-i586.bin into a directory jre1.6.0_23. Move this directory to /opt/
# mv jre1.6.0_23/ /opt/
use alternative command to make oracle java JRE a default java environment:
alternatives --install /usr/bin/java java /opt/jre1.6.0_23/bin/java 20000