Changing the default Java for linux

I have an linux OS (CentOS 5.6) installed on my machine. And I have worked with java 1.4.2 there but now I'm going to use new JDK 1.6. I have installed java 1.6.0, but running

#java -version

I still got

1.4.2.

How to fix it?

Also id you tried some manual edition, you can get the following error:

# java -version

java: error while loading shared libraries: libjli.so: cannot open shared object file: No such file or directory
We are going to fix this issue as well

So, lets start an alternatives application with --install key and specify where the new version of java is installed. Let's assume the new java folder is  /usr/local/jdk1.6.0_45/ and the old one is  /usr/local/jdk1.4.2/

So, type:

# alternatives --install /usr/bin/java java /usr/local/jdk1.6.0_45/bin/java 2

This says to Linux that we have installed new java and executable file is  /usr/local/jdk1.6.0_45/bin/java and now we are going make selection of the default java:

#alternatives --config java

You will see the following:

There are 2 programs which provide 'java'.

Selection Command
-----------------------------------------------
* 1  /usr/local/jdk1.4.2/bin/java
+ 2 /usr/local/jdk1.6.0_45/bin/java

 Enter to keep the current selection[+], or type selection number:

The dafault one is marked by *, and you just have to enter the number of line with desired version (2 in our case)

Checking it out:

# java -version
java version "1.6.0_45"