configure java alternatives

 $ java -version
 gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-44)
 $ alternatives --install /usr/bin/java java /usr/java/jre1.6.0_14/bin/java 2
 $ 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
 $ java -version
 Java HotSpot(TM) Client VM (build 14.0-b16, mixed mode, sharing)