yes, you need java.
If you try to open anything that requires it (and you don't have it), you will get a prompt to install it. Another way to check is to go to your Applications folder > Utilities > Java Preferences and open that. If you don't have it, you will get this prompt:
As you can see, I don't have it and have not come across anything that needs it. The only thing you do need is Java Script which is different - it is by default enabled in Safari:
I intend to only install Java if it is necessary and then, once done, try to disable it.