I've been answering questions on this forum for a couple of days now and I'm seeing a trend. A good portion of the questions can be answered by referring to the Java API documentation at
Java Platform SE 6
I've been developing Java applications for years and I always have a page open to the Java API docs. One thing that Sun did very well was that they thoroughly documented the API. Every class in the JRE is documented and usually come with some examples on how to use them. The API docs should be the first place any Java developer goes for information.
I'm not saying that you cannot post questions here. It is just a good idea to familiarize yourself with the API docs as they will be invaluable to you in the future.