This might be a really trivial question, but I've been writing Java programs at my school. But I just found out that I can create websites with Java as well. How can I do that? Any good books/tutorials for that? Also, I know about PHP, which is better for Web development? Also, when using PHP, MySQL comes into picture and while writing Java programs for desktop, we just use File I/O, so what is better for web dev, File I/O or MySQL?
Thank you.
Read the tutorial on Java Web applications.
Basically Web applications are a part of the J2EE standard. A lot of people only use the Web (servlets) part with additional frameworks thrown in, most notably Spring but also Struts, Seam and others.
All you need is an IDE like IntelliJ, Eclipse or Netbeans, the JDK, the JEE download and a servlet container like Tomcat (or a full-blown application server like Glassfish or JBoss).
Here is a Tomcat tutorial.
You are asking a few different questions...
The simplest way to start making websites with Java is to use JSP. JSP stands for Java Server Pages, and it allows you to embed Java code within HTML files for dynamic page creation. In order to compile and serve JSPs, you will need a Servlet Container, which is basically a web server that runs Java classes. The most popular basic Servlet Container is called Tomcat, and it's provided free by The Apache Software Foundation. Follow the tutorial that cletus provided here.
Once you have Tomcat up and running, and have a basic understanding of how to deploy JSPs, you'll probably want to start creating your own JSPs. I always like IBM developerWorks tutorials. They have a JSP tutorial here that looks alright (though a bit dated).
You'll find out that there is a lot more to Java web development than JSPs, but these tutorials will get you headed in the right direction.
This is a pretty subjective question. PHP and Java are just tools, and in the hands of a bad programmer, any tool is useless. PHP and Java both have their strengths and weaknesses, and the discussion of them is probably outside of the scope of this post. I'd say that if you already know Java, stick with Java.
MySQL is better suited for web applications, as it is designed to handle many concurrent users. You should know though that Java can use MySQL just as easily as PHP can, through JDBC, Java's database connectivity framework.
Also be advised, that while Java is in general very beginner friendly, getting into JavaEE, Servlets, Facelets, Eclipse integration, JSP and getting everything in Tomcat up and running is not. Certainly not the easiest way to build a website and probably way overkill for most things.
On top of that you may need to host your website yourself, because most webspace providers don't provide Servlet Containers. If you just want to check it out for fun, I would try Ruby or Python, which are much more cooler things to fiddle around with. But anyway, to provide at least something relevant to the question, here's a nice Servlet tutorial: link
I think GWT should also be mentioned, it simplifies some things and reduces the need for javascript
While a lot of others should be mentioned, Apache Wicket should be preferred.
Wicket doesn't just reduce lots of boilerplate code, it actually removes it entirely and you can work with excellent separation of business code and markup without mixing the two and a wide variety of other things you can read about from the website.
I'll jump in with the notorious "Do you really want to do that" answer.
It seems like your focus is on playing with Java and seeing what it can do. However, if you want to actually develop a web app, you should be aware that, although Java is used in web applications (and in serious ones), there are other technology options which might be more adequate.
Personally, I like (and use) Java for powerful, portable backend services on a server. I've never tried building websites with it, because it never seemed the most obvious ting to do. After growing tired of PHP (which I have been using for years), I lately fell in love with Django, a Python-based web framework.
The Ruby on Rails people have a number of very funny videos on youtube comparing different web technologies to RoR. Of course, these are obviously exaggerated and maybe slightly biased, but I'd say there's more than one grain of truth in each of them. The one about Java is here. ;-)
I'd suggest OOWeb to act as an HTTP server and a templating engine like Velocity to generate HTML. I also second Esko's suggestion of Wicket. Both solutions are considerably simpler than the average setup.
Look into creating Applets if you want to make a website with Java. You most likely wont need to use anything but regular Java, unless you want something more specialized.