Why is java on windows 7

What you have is the Java runtime environment, needed by many internet web pages and web apps.

Leave it alone and let update when it wants too.

It can be deleted. As the other mentioned, it's ok to leave it though, its normal to have.

I use it in development when I'm writing java apps for my servers and as a runtime when using certain java based apps in Windows but all those uses are ones I specifically need. It's common to have it installed on your machine. Odds are you'll use it from time to time in your browser but unless your bank requires it for authentication you can do without. If you need it for something you'll find out at the time. I disabled it in all my browsers and remove the jsched update program that likes to load with the operating system.

It's small, it's clean, it's used more often that you'd think so just leave it where it is an update it whenever it asks.

Last thing I want while gaming is java going out to look for updates!
If it doesn't have an option to turn off updates, I uninstall or stop from starting.

almost.
don't leave it alone.
take it out of your start-up and tell it not to look for updates.
check for updates manually and it only takes a second to load when needed.
and when it's running, it will notify of updates anyhow.
but yes, keep Java for you will need it regardless of being a developer or not..