1. install the newest JDK rpm (available from sun.com)
2. type the following:

/usr/sbin/alternatives --install /usr/bin/java java /usr/java/latest/bin/java 0 \
    --slave /usr/bin/javac javac /usr/java/latest/bin/javac \
    --slave /usr/bin/keytool keytool /usr/java/latest/bin/keytool \
    --slave /usr/bin/rmiregistry rmiregistry /usr/java/latest/bin/rmiregistry

/usr/sbin/alternatives --set java /usr/java/latest/bin/java


/usr/sbin/alternatives --install /usr/bin/javac javac /usr/java/latest/bin/javac 0 \
    --slave /usr/bin/javadoc javadoc /usr/java/latest/bin/javadoc \
    --slave /usr/bin/javah javah /usr/java/latest/bin/javah \
    --slave /usr/bin/jar jar /usr/java/latest/bin/jar \
    --slave /usr/bin/jarsigner jarsigner /usr/java/latest/bin/jarsigner \
    --slave /usr/bin/appletviewer appletviewer /usr/java/latest/bin/appletviewer

/usr/sbin/alternatives --set javac /usr/java/latest/bin/javac

ln -sf /usr/java/latest/jre/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/mozilla/plugins/