Why use Java Enum as class attributes?

From the sample entity code from ADF, I notice that an Enum class is used to contain all attributes of a class (as below). What are the benefits of using Enum here and not the traditional declaration {int EmpId, public int getEmpId(), public void setEmpId(int)} ; ? If this is a design pattern, what pattern is it? Thank you.
public class EmployeeImpl extends EntityImpl {
public enum AttributesEnum {
EmpId {
public Object get(UsersImpl obj) {
return obj.getUserId();
public void put(UsersImpl obj, Object value) {
obj.setUserId((DBSequence)value);
}

I've used InstallAnywhere Now! to deploy basic apps to friends before. You can find it here:
http://www.zerog.com/downloads_05.html
It takes care of making your program executable on most operating systems. If you get any jvm errors when running the installer it creates for you then try packaging your program with a specific JVM. The size of your setup file will be a quite a bit larger, but if you're putting it on cd it shouldn't matter. I had a similar problem with InstallSheild when I tried it (maybe it was just me). Anyway, I decided to use this one because it was free and the program I used it for was written for a friend (that I didn't charge :-)
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Why use Java Enum as class attributes?

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