ip changing using java

hi friends....

I changed the ip of the system using the code " Runtime.getRuntime().exec("ifconfig eth0 192.168.0.04"); ". After this when ifconfig is run from the terminal, i got the new ip. But using InetAddress.getLocalHost(), i am getting the old one. what could be the problem ????
And is there any other way to change the ip of the system in java ????

THANKS IN ADVANCE....


sanu