What version of Java is realistic to expect on a client/browser?

Question

I'm planning to develop an applet-based application that will be used by "average Jill" non-technical users (classical musicians, to be precise). What version of Java can I realistically expect those users to have installed in their browsers? Is 1.5 safe? I know Microsoft hasn't bundled Java with Windows in years, but do most OEM Windows machines have it? What about Macs?

I realize if I use the standard deployment techniques it can prompt the user to install Java if they don't have it or their version is too old for my code, but I'd still like to have a sense of what features I can realistically code for without most users having to install anything. Thanks,

Edit: one other thing not covered by the earlier question: how common is it for Windows users not to have Java at all in this day and age?

Answer 1

Very difficult to tell. Java 5 has been out for years but may not be universally available.

Java 6 would be even better, it is vastly improved as far as the client experience is concerned.

Answer 2

Definitely Java 5 or higher. JDK 1.4 went out of support in Oct 2008, over thirteen months ago.

Answer 3

Java 5. If you target macs (average user), you won't get Java 6.

Answer 4

I think that it's fairly unreasonable to suspect that anyone who doesn't develop in Java to have it installed. I have it installed on two of the six computers I use regularly, and even then I plan to uninstall it from both once I finish working on the small side project that I started recently. My parents don't have it installed on their computers, and they'll install anything and everything they can find on the internet. The only site I've visited in years that has even had a Java applet on it is Facebook.

Internet Explorer, Firefox, and Chrome don't come with Java. Nothing on the web uses Java. I don't expect any recent computer to have it anymore, though if you can gather stats on the actual visitors of your site, you'll be better off.