Which came first, Amazon or Java?

Amazon came first, by one year. Jeff Bezos incorporated the company in Washington state.

Side by side

Amazon

Amazon was incorporated on 5 July 1994, originally as Cadabra, and the website opened in July 1995 selling only books. The 1994 incorporation date is used here because it is the company's own founding date; if you mean the shop, 1995 is the answer. Either way it predates Google by three or four years and eBay by about a year.

Java

Java was announced in May 1995, having started in 1991 as a project called Oak aimed at interactive television — a market that did not exist yet. Its promise was "write once, run anywhere", achieved by compiling to bytecode for a virtual machine rather than to a specific processor. JavaScript arrived seven months later and was named after it purely as a marketing decision; the two languages are unrelated.