Okay, I will try to answer this. Hope its not an overkill. Lets look at the source code for DateFormat class
here
Look at the package of that class. We are interested in "java.text.DateFormat"
Go to your
java installation folder. It looks like jdk<some number here>. Find the file src.zip. Extract its contents. Follow this path - java.text.
DateFormat. Open the file. Find getDateInstance() or getDateInstance(int abc).
Its calling get(XXX)...search for that method.
Abstract class cannot be instantiated. So, it does NOT return an Object of DateFormat which is an abstract class. But, it returns and Object of SimpleDateFormat. Lets see what SimpleDateFormat is all about.
We look at SimpleDateFormat
here
public class SimpleDateFormat
extends DateFormat
It
IS A type of DateFormat. Its a class which can be instantiated.
Hope it makes sense.