A script to detect the installed Oracle JDK 7 and set alternatives to use the ones from the latest Oracle JDK 7. Tested on CentOS 6.4.

update-java-alternatives.sh

#!/bin/bash

## locate the JDK
JDK=$(basename $(ls -l -d /usr/java/jdk1.* | awk '{print $NF}' | tail -n 1))

[[ -z $JDK ]] && echo "No Oracle JDK 7 installed in /usr/java" 1>&2 && exit 1

## java
alternatives --install /usr/bin/java java /usr/java/${JDK}/jre/bin/java 20000
alternatives --set java /usr/java/${JDK}/jre/bin/java

## javaws
alternatives --install /usr/bin/javaws javaws /usr/java/${JDK}/jre/bin/javaws 20000
alternatives --set javaws /usr/java/${JDK}/jre/bin/javaws

## javac
alternatives --install /usr/bin/javac javac /usr/java/${JDK}/bin/javac 20000
alternatives --set javac /usr/java/${JDK}/bin/javac

## jar
alternatives --install /usr/bin/jar jar /usr/java/${JDK}/bin/jar 20000
alternatives --set jar /usr/java/${JDK}/bin/jar

if [[ $(uname -m) == "x86_64" ]]; then
    ## Java browser plugin 64 bit
    alternatives --install /usr/lib64/mozilla/plugins/libjavaplugin.so libjavaplugin.so.x86_64 /usr/java/${JDK}/jre/lib/amd64/libnpjp2.so 20000
else
    ## Java browser plugin 32 bit
    alternatives --install /usr/lib/mozilla/plugins/libjavaplugin.so libjavaplugin.so /usr/java/${JDK}/jre/lib/i386/libnpjp2.so 20000
fi