Cannot Uninstall Java
You are trying to upgrade java and cannot as the previous version is corrupt. I came accross this issue recently when i was trying to uninstall a corrupt version of java then reinstall.
After a bit of searcing I found this JavaRA. It does exactly what you want to do it removes java for you then puts the latest version on all with a single click
Update the Java JRE at the click of a button. JavaRa is a simple tool that does a simple job: it removes old and redundant versions of the Java Runtime Environment (JRE).