Static nested class in Java, why?

Question

I was looking at the Java code for LinkedList and noticed that it made use of a static nested class, Entry.

public class LinkedList<E> ... {
...

 private static class Entry<E> { ... }

}

What is the reason for using a static nested class, rather than an normal inner class?

The only reason I could think of, was that Entry doesn't have access to instance variables, so from an OOP point of view it has better encapsulation.

But I thought there might be other reasons, maybe performance. What might it be?

Note. I hope I have got my terms correct, I would have called it a static inner class, but I think this is wrong: http://java.sun.com/docs/books/tutorial/java/javaOO/nested.html

Answer 1

Non static inner classes can result in memory leaks while static inner class will protect against them. If the outer class holds considerable data, it can lower the performance of the application.