$ls -l /usr/bin/java
/usr/bin/java -> /etc/alternatives/java
$ls -l /etc/alternatives/java
/etc/alternatives/java -> /usr/lib/jvm/jre-1.6.0-sun/bin/java
If we type command java on command prompt then /usr/bin/java is invoked. The /usr/java/bin points to /etc/alternatives/java and /etc/alternatives/java points to /usr/lib/jvm/jre-1.6.0-sun/bin/java. So the target of the command java becomes /usr/lib/jvm/jre-1.6.0-sun/bin/java
On Ubuntu, there is a graphical utility which lets you to change/configure the alternatives. But this is missing from the default install of openSUSE. But on the openSUSE this can be easily achieved by command line as -
update-alternatives --config java
This command will list all available options and will ask you to enter to select one of them.