vim .bashrc

export JAVA_HOME=/var/lib/jdk1.6

export PATH=$PATH:$JAVA_HOME/bin

export CLASSPATH=$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar

source .bashrc

update-alternatives --install /var/lib/jdk1.6/bin/java java /var/lib/jdk1.6/bin/ 300

java -version

#success done!!!