title: how to remove open-jdk completely in ubuntu?
body: <p>I hava installed oracle-jdk,so want to remove openjdk completely to ensure every java-based apps will use oracle jdk,but when I try to run "sudo apt-get remove openjdk-6-<em>",ubuntu will remove openjdk-6 but try to install openjdk-7-</em> at the same time automatically.
     So,how to remove openjdk-6 and stop ubuntu to install openjdk-7 at the same time.</p>