Installing jars and classes

Question

I just started learning Java (I used books like "Teach yourself java 2 in 24 hours", "Teach yourself java in 21 days", "Teach yourself object oriented programming in 21 days", etc.), but there are still some things that prevent me from succeeding. I have programmed in PHP, Javascript and StarBasic before.
I'm testing some Swing component. I wanted to use a JFormattedTextField with a MaskFormatter over it. But it seems that I don't have the class installed.
My Code
import javax.swing.JFormattedTextField.*;
import javax.swing.text.MaskFormatter;
MaskFormatter formatter = new MaskFormatter("(###) ###-####");
JFormattedTextField textField = new JFormattedTextField(formatter);Error message: Type MaskFormatter not found
How can I check if the class is installed? I use a Linux deriviant Kubuntu. I looked at /usr/share/java/ , where I find a lot of jars, but none applicable. How do I even know what my classpath is?

Answer 1

I use Sun Java 6. This compiles without error for me:
import javax.swing.text.MaskFormatter;
public class XXX
    public static void main(String[] args) throws java.text.ParseException
        MaskFormatter formatter = new MaskFormatter("(###) ###-####");
}