Debian updating java
Java Update can only be run if the system is connected to the internet.
To make Java 8 default, you must install the "oracle-java8-set-default" package (which configures the Java environment variables and sets it as default), which I added as a "Recommended" package to "oracle-java8-installer".
So, if you want to set Oracle Java 8 as default, no matter what other Java versions are installed, make sure that you install the oracle-java8-set-default package (which, again, should be automatically installed with the main Oracle Java Installer package in Ubuntu, but not in Linux Mint): If you don't want to make Oracle Java 8 default (it might still be set as default, depending on what other Java versions you may have installed), install the oracle-java8-installer with "--no-install-recommends": Note: removing the oracle-java8-set-default package does not undo all the changes (I have yet to find a way to do this properly).
If you don't want to set it as default, remove both oracle-java8-installer and oracle-java8-set-default packages, and then install oracle-java8-installer with "--no-install-recommends" (like mentioned above).
Monthly updates check weekly and notify you within 30 days that an update is available, however, if an update is considered critical you are notified within a week of its release.
From the Java Control Panel Update tab, you can manually check for an update any time by clicking on the Update Now button located at the bottom of the Update tab on the Java Control Panel.
Java Update is a feature that keeps your Windows computer up-to-date with the latest Java releases.