Using etc alternatives to set default Java on CentOS

gistfile1.sh

[user@www]# alternatives --install /usr/bin/java java /opt/jdk1.6.0_07/bin/java 2
[user@www]# alternatives --config java
 
There are 2 programs which provide 'java'.
 
  Selection    Command
-----------------------------------------------
*+ 1           /usr/lib/jvm/jre-1.4.2-gcj/bin/java
   2           /opt/jdk1.6.0_07/bin/java
 
Enter to keep the current selection[+], or type selection number: 2
[user@www]#