wget --no-cookies --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F" " http://download.oracle.com/otn-pub/java/jdk/7u21-b11/jdk-7u21-linux-x64.tar.gz "
tar xzf jdk-7u21-linux-x64.tar.gz
sudo mv jdk1.7.0_21 /usr/lib/jvm/
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.7.0_21/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.7.0_21/bin/javac" 1
# interactive selection
sudo update-alternatives --config java
# interactive selection
sudo update-alternatives --config javac
# test
java -version