Java was introduced in Netscape Navigator 2 at the same time as JavaScript. But Java was really not integrated with the html at all. It lived in its own isolated box on the page. JavaScript was integrated with html and with the browser environment.

Maybe as a plugin, but from what i can tell Javascript was the first to be supported natively: http://www.javascripter.net/faq/javascr3.htm

I think the TCL plugin predates the Java one.